Hydrocarboxylation of formaldehyde in the presence of a higher order carboxylic acid and a homogeneous catalyst

ABSTRACT

Disclosed is a process for the production and purification of glycolic acid or glycolic acid derivatives by the carbonylation of formaldehyde in the presence of a homogeneous acid catalyst and a carboxylic acid. This invention discloses hydrocarboxylations and corresponding homogeneous acid catalyst and glycolic acid separations. The homogeneous acid catalyst is readily separated from the hydrocarboxylation reaction effluent and recycled and the carboxylic acid is readily removed from the glycolic acid and the carboxylic acid is recycled.

FIELD OF THE INVENTION

This invention relates to a process for the production and purificationof glycolic acid or glycolic acid derivatives by the carbonylation offormaldehyde in the presence of a homogeneous acid catalyst and acarboxylic acid. This invention discloses hydrocarboxylations andcorresponding homogeneous acid catalyst and glycolic acid separationswherein the homogeneous acid catalyst is readily separated from thehydrocarboxylation reaction effluent and recycled and the carboxylicacid is readily removed from the glycolic acid and the carboxylic acidis recycled.

BACKGROUND OF THE INVENTION

Glycolic acid (also known as 2-hydroxyacetic acid or α-hydroxyaceticacid) can be used for many purposes including as a raw material to makeethylene glycol. Glycolic acid is prepared by the acid catalyzedreaction of carbon monoxide and formaldehyde in the presence of water,alcohols, and/or carboxylic acids. These processes often require hightemperatures and pressures to proceed at practical rates. For example,glycolic acid typically is prepared by reacting formaldehyde with carbonmonoxide and water in the presence of an acidic catalyst such assulfuric acid under high temperature and pressure such as, for example,above 480 bar absolute (abbreviated herein as “bara”), and between 200and 225° C. Alternatively, lower pressures may be employed in thepresence of hydrogen fluoride as a catalyst and solvent. Theseprocesses, however, require expensive materials of construction and/orrecovery and recycling schemes for hydrogen fluoride. Furthermore,readily available and less expensive formaldehyde starting materialtypically contains large concentrations of water that inhibit the rateof the carbonylation reaction and make purification of the glycolic acidproduct difficult. Separation of glycolic acid and the carboxylic acidis not feasible using distillation methods because the glycolic acidreacts with the carboxylic acid under typical process temperatures.Acetic acid is similar in its hydrophobicity to glycolic acid, makingextraction methods unattractive for separating glycolic acid and aceticacid. Thus, there is a need for an economical process for makingglycolic acid from an aqueous formaldehyde starting material that can beaccomplished at moderate temperatures and pressures and allows for theready separation of the glycolic acid from the crude hydrocarboxylationreactor product.

SUMMARY OF THE INVENTION

The present invention provides in a first embodiment a process for thepreparation of glycolic acid, comprising

-   -   (A) feeding carbon monoxide, aqueous formaldehyde, a homogeneous        acid catalyst, and a carboxylic acid comprising 3-6 carbon atoms        to a hydrocarboxylation reaction zone to produce an effluent        comprising said homogeneous acid catalyst and esters of glycolic        and carboxylic acids;    -   (B) recovering the homogeneous acid catalyst from the effluent        by extracting the effluent with a first hydrophilic solvent to        form a first aqueous extract phase comprising a major amount of        the homogeneous acid catalyst contained in the effluent and a        first organic raffinate phase comprising a major amount of the        esters of glycolic and carboxylic acids contained in the        effluent;    -   (C) separating the first organic raffinate phase and the first        aqueous extract phase; and    -   (D) recycling the first aqueous extract phase to step (A).

The present invention provides in a second embodiment a process for thepreparation of glycolic acid, comprising

-   -   (A) feeding carbon monoxide, aqueous formaldehyde, a homogeneous        acid catalyst, and a carboxylic acid selected from at least one        of the group consisting of propionic acid, n-butyric acid,        i-butyric acid, 2-methyl butyric acid, n-valeric acid, and        i-valeric acid to a hydrocarboxylation reaction zone to produce        an effluent comprising the homogeneous catalyst and esters of        glycolic and carboxylic acids;    -   (B) recovering the homogeneous acid catalyst from the effluent        by extracting the effluent with a first hydrophilic solvent        comprising 15 weight percent to 100 weight percent water and 0        weight percent to 85 percent of glycolic acid, each on a total        first hydrophilic solvent weight basis, and optionally with a        first hydrophobic solvent selected from at least one of the        group consisting of hexane, cyclohexane, heptane, octane,        decane, benzene, toluene, xylene, isoparaffinic mixed        hydrocarbons having a boiling range between 90 and 325° C.,        methyl naphthalene, diethyl ether, dipropyl ether, diisopropyl        ether, dibutyl ether, methyl tertiary-butyl ether, and methyl        tertiary-amyl ether to form a first aqueous extract phase        comprising a major amount of the homogeneous acid catalyst        contained in the effluent and a first organic raffinate phase        comprising a major amount of the esters of glycolic and        carboxylic acids contained in the effluent;    -   (C) separating the first organic raffinate phase and the first        aqueous extract phase; and    -   (D) recycling the first aqueous extract phase to step (A).

DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic of an embodiment of the present invention forhydrocarboxylation of an aqueous formaldehyde feed using a homogeneousacid catalyst in valeric acid.

DETAILED DESCRIPTION

The present invention provides in a first embodiment a process for thepreparation of glycolic acid, comprising

-   -   (A) feeding carbon monoxide, aqueous formaldehyde, a homogeneous        acid catalyst, and a carboxylic acid comprising 3-6 carbon atoms        to a hydrocarboxylation reaction zone to produce an effluent        comprising said homogeneous acid catalyst and esters of glycolic        and carboxylic acids;    -   (B) recovering the homogeneous acid catalyst from the effluent        by extracting the effluent with a first hydrophilic solvent to        form a first aqueous extract phase comprising a major amount of        the homogeneous acid catalyst contained in the effluent and a        first organic raffinate phase comprising a major amount of the        esters of glycolic and carboxylic acids contained in the        effluent;    -   (C) separating the first organic raffinate phase and the first        aqueous extract phase; and    -   (D) recycling the first aqueous extract phase to step (A).

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe following specification and attached claims are approximations thatmay vary depending upon the desired properties sought to be obtained bythe present invention. At the very least, each numerical parametershould at least be construed in light of the number of reportedsignificant digits and by applying ordinary rounding techniques.Further, the ranges stated in this disclosure and the claims areintended to include the entire range specifically and not just theendpoint(s). For example, a range stated to be 0 to 10 is intended todisclose all whole numbers between 0 and 10 such as, for example 1, 2,3, 4, etc., all fractional numbers between 0 and 10, for example 1.5,2.3, 4.57, 6.1113, etc., and the endpoints 0 and 10. Also, a rangeassociated with chemical substituent groups such as, for example, “C₁ toC₅ hydrocarbons”, is intended to specifically include and disclose C₁and C₅ hydrocarbons as well as C₂, C₃, and C₄ hydrocarbons.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

It is to be understood that the mention of one or more process stepsdoes not preclude the presence of additional process steps before orafter the combined recited steps or intervening process steps betweenthose steps expressly identified. Moreover, the lettering of processsteps or ingredients is a convenient means for identifying discreteactivities or ingredients and the recited lettering can be arranged inany sequence, unless otherwise indicated.

As used herein the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itself,or any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

The term “glycolic acid”, as used herein, refers to the chemicalcompound, glycolic acid, also known as 2-hydroxyacetic acid. The term“glycolic acid oligomers”, as used herein, refers to the reactionproducts of glycolic acid with itself, particularly the linear or cyclicesters formed by a reaction between the carboxyl group of one moleculeand the alcohol group of another molecule. The “glycolic acid oligomers”include, but are not limited to, (2-hydroxyacetoxy)acetic acid (G2),2-(2′-hydroxyacetoxy)acetoxyacetic acid (G3), and2-(2′-(2″-hydroxyacetoxy)acetoxy)acetoxyacetic acid (G4). The term“esters of glycolic and carboxylic acids”, as used herein, refers to theesters produced by the reaction of a carboxylic acid with the hydroxylend of glycolic acid and/or its oligomers.

The term “hydrocarboxylation reaction zone”, as used herein, refers tothe part of the process wherein the carbon monoxide, aqueousformaldehyde, homogeneous acid catalyst, and carboxylic acid are fed,and esters of glycolic and carboxylic acids are produced. The term“effluent”, as used herein, refers to the liquid stream exiting thehydrocarboxylation reaction zone comprising the homogeneous acidcatalyst and the “esters of glycolic and carboxylic acids”.

The term “homogeneous acid catalyst”, as used herein, refers to an acidcatalyst that is soluble or partly soluble in the reaction mixture underreaction conditions. The homogeneous acid catalyst may be a Brønsted orLewis acid as further described below.

The term “hydrolyzing”, as used herein, refers to reacting with water.The term “hydrolyzed mixture”, as used herein, refers to the firstorganic raffinate phase after “hydrolyzing” it; the “hydrolyzed mixture”comprises glycolic acid and carboxylic acid that are the product of“hydrolyzing” the “esters of glycolic and carboxylic acids”.

The term “extracting”, as used herein, refers to separating a componentfrom a feed into an immiscible liquid based upon relative differences insolubility. As used herein, the term “feed” is intended to have itscommonly understood meaning in the liquid-liquid extraction art, whichis the solution that contains the materials to be extracted orseparated. The term “extraction solvent”, as used herein, is intended tobe synonymous with the term “extractant” or “solvent” and is intended tomean the immiscible liquid that is used in the extraction process toextract materials or solutes from the feed. The term “extract” is theimmiscible liquid left from the extraction solvent after it has beencontacted with the feed. The term “raffinate” is intended to mean theliquid phase left from the feed after it has been contacted with theextraction solvent. The term “wash solvent” is understood to mean aliquid used to wash or enhance the purity of the raffinate or extractphase.

The term “hydrophobic solvent”, as used herein, refers to a solvent thatwill phase separate when mixed with water. In the present invention,examples of hydrophobic solvents are “esters”, “ethers”, “ketones”, and“hydrocarbons” which are terms well known to those skilled in the art.In the present invention, the extracting of step (B) using a firsthydrophilic solvent produces a first organic raffinate phase and a firstaqueous extract phase. The term a “major amount”, as used herein, forexample “a major amount of the homogenous acid catalyst contained in theeffluent” refers to at least 50 weight percent of the homogenous acidcatalyst contained in the effluent. In a further example, when a firstaqueous extract phase comprises a major amount of the homogeneous acidcatalyst contained in the effluent, the weight of the homogenous acidcatalyst in the first aqueous extract phase divide by the weight of thehomogenous acid catalyst in the effluent is at least 50 weight percent.The term a “minor amount”, as used herein, for example “a minor amountof homogenous acid catalyst contained in the effluent” refers to lessthan 50 weight percent of the homogenous acid catalyst in the effluent.The term “hydrophilic solvent”, as used herein, refers to a solvent thatis miscible with water.

The term “molar ratio”, as used herein, refers to the moles of onecomponent divided by the moles of another component. For example, if themolar ratio of carboxylic acid to formaldehyde is 2:1, then for everymole of formaldehyde, there are two moles of carboxylic acid. Note thatthe water in any aqueous formaldehyde feed is not considered in themolar ratio of carboxylic acid to formaldehyde.

The terms “reactions of ethylene glycol and glycolic acid”, and“reacting ethylene glycol and glycolic acid”, and “reacting ethyleneglycol with a second aqueous raffinate phase” which comprises glycolicacid, as used herein, refer to the many reactions that occur whenethylene glycol and glycolic acid are present at typical reactionconditions. The reactions include reactions between ethylene glycol andglycolic acid and reactions of glycolic acid with itself. Additionally,the reactions include reactions between ethylene glycol, glycolic acid,and glycolic acid oligomers or other reaction products such as2-hydroxyethyl 2-hydroxyacetate. The term “glycolate ester oligomers”,as used herein, refers to the many reaction products of glycolate estersformed by “reacting ethylene glycol and glycolic acid”. Examplesinclude, but are not limited to 2-hydroxyethyl 2-hydroxyacetate,1,2-ethanediyl bis(2-hydroxyacetate),2′-[2″-(2′″-hydroxyacetoxy)acetoxy]ethyl 2-hydroxyacetate,2′-(2″-[2″-(2″″-hydroxyacetoxy)acetoxy]acetoxy)ethyl 2-hydroxyacetate,2″-hydroxyethyl (2′-hydroxyacetoxy)acetate, 2′″-hydroxyethyl2′-(2″-hydroxyacetoxy)acetoxyacetate, and 2″″-hydroxyethyl2′-[2″-(2′″-hydroxyacetoxy)acetoxy]acetoxyacetate.

The aqueous formaldehyde used in the hydrocarboxylation reactiontypically comprises 35 to 85 weight percent formaldehyde. Other examplesof formaldehyde levels in the aqueous formaldehyde feed are 40 to 70weight percent and 40 to 60 weight percent. These ranges are typicalconcentrations that can be achieved with conventional formaldehydeprocesses without further distillation. Conventional formaldehydeprocesses are described in “Formaldehyde”, Kirk-Othmer Encyclopedia,Vol. 11, 4^(th) Edition, 1994. For example, commercially availableformaldehyde typically contains approximately 55 weight percentformaldehyde in water. Other forms of formaldehyde may be present in theaqueous formaldehyde feedstock including trioxane or paraformaldehydeand linear oligomers and polymers of formaldehyde, i.e.,poly(oxymethylene) glycols and derivatives thereof, formed from thepolymerization or oligomerization of formaldehyde in water or othersolvents. The term “formaldehyde”, as used herein, is intended toinclude all the various forms of formaldehyde described above.

The advantages of using a homogenous acid catalyst over a heterogeneouscatalyst include cost, fewer deactivation mechanisms, no physicalattrition, and the ability to use higher catalyst concentrations. Thepresence of at least one acid catalyst, although not required for thereaction to proceed, greatly increases the rate of the carbonylationreaction and at the expense of side reactions. The homogeneous acidcatalyst may be of the Lewis or Brønsted types that are well understoodby persons skilled in the art. Homogeneous acid catalysts that areactive in promoting the carbonylation process generally have pKa valuesin aqueous solution of less than 7. For example, homogeneous acidcatalysts that have a pKa value in aqueous solution of 5 may be used.Further examples of homogeneous acid catalysts are those having a rangeof pKa values in aqueous solution of from −10 to 3, and −10 to 1.Representative examples of homogeneous acid catalysts are sulfonicacids, mineral acids, carboxylic acids, inorganic acid salts, andcombinations thereof. Some more specific examples of homogeneous acidcatalysts include, but are not limited to, hydrochloric acid,hydrobromic acid, hydroiodic acid, hydrofluoric acid, perchloric acid,phosphoric acid, nitric acid, sulfuric acid, sulfonic acids, acid metalsulfates and acid metal phosphates comprising one or more metals fromGroups 1 and 2 of the Periodic Table of the Elements, methanesulfonicacid, trifluoro-methanesulfonic acid, fluorosulfonic acid,chlorosulfonic acid, methanedisulfonic acid,methylsulfonylmethanesulfonic acid, methanetrisulfonic acid,bis(methylsulfonyl)methanesulfonic acid,1,1,2,2-tetrafluoroethanesulfonic acid, nonafluorobutanesulfonic acid,bis(trifluoromethyl)sulfonylamide, p-toluenesulfonic acid,benzenesulfonic acid, and combinations thereof. In another aspect, thehomogenous acid catalyst is selected from at least one of the groupconsisting of sulfuric acid, trifluoromethanesulfonic acid,1,1,2,2-tetrafluoroethanesulfonic acid,bis(trifluoromethyl)sulfonylamide, and nonafluorobutanesulfonic acid. Inanother aspect, the homogenous acid catalyst comprisestrifluoromethanesulfonic acid.

The homogeneous acid catalyst may be used in amounts ranging from 0.02to 1.0 mole of homogeneous acid catalyst per mole of formaldehyde.Another example of acid catalyst levels is 0.02 to 0.15 mole of acidcatalyst per mole of formaldehyde. Proportions higher than 1.0 mole ofcatalyst per mole of formaldehyde, however, may be used in manyinstances, such as, for example, in processes in which the catalyst alsofunctions as a solvent. Hydrochloric acid and sulfuric acid may be usedin this fashion. Such catalysts may be employed in amounts up to andeven greater than molar proportions with the formaldehyde, but it may beeasier to effect the separation of the glycolic acid or esters ofglycolic and carboxylic acids from the reaction mixture if lesseramounts of catalyst are employed.

The rate and yield of hydrocarboxylation may be enhanced by conductingthe reaction in the presence of a compound of Cu(I) or of Ag(I). Forexample, the reaction mixture can comprise sulfuric acid,methanesulfonic acid, trifluoroacetic acid, hydrochloric acid, ortrifluoromethanesulfonic acid as the homogeneous acid catalyst and Cu(I)or Ag(I). The Cu(I) and Ag(I), typically, can be added to the reactionmixture in elemental form or as their corresponding oxides or metalsalts.

In the process of the present invention, the carboxylic acid serves as asolvent and promoter for the hydrocarboxylation reaction. The carboxylicacid will react in the hydrocarboxylation reaction zone to form acorresponding acyloxyacetic acid. For example, acetic acid can react toform acetoxyacetic acid, propionic acid can react to form2-propionoxyacetic acid, and the like. The acyloxyacetic acids arehydrolyzed to produce glycolic acid and the carboxylic acid. Thecarboxylic acid is chosen to give the best improvement to thehydrocarboxylation reaction conversions and reaction selectivities whilesimultaneously providing easy separation between the glycolic acid andcarboxylic acid. In one example, the carboxylic acid comprises 3 to 6carbon atoms. In another example, the carboxylic acid comprises 3 to 5carbon atoms. The carboxylic acid can be one or more of propionic acid,n-butyric acid, i-butyric acid, 2-methyl butyric acid, n-valeric acid,and i-valeric acid. In one example, the carboxylic acid comprisespropionic acid. In another aspect, the carboxylic acid can be one ormore of 2-methyl butyric acid, n-valeric acid, and i-valeric acid. Inanother example, the carboxylic acid comprises n-valeric acid.

In the process of the present invention the molar ratio of carboxylicacid to formaldehyde (carboxylic acid:formaldehyde) fed to thehydrocarboxylation zone can vary over a considerable range. Examplesinclude feeding at a carboxylic acid:formaldehyde of from 0.2:1 to 10:1,or 0.2:1 to 6:1, or 0.2:1 to 4:1, or 0.2:1 to 2.5:1, or 0.2:1 to 2:1, or0.5:1 to 10:1, or 0.5:1 to 6:1, or 0.5:1 to 4:1, or 0.5:1 to 2.5:1, or0.5:1 to 2:1, or 0.7:1 to 10:1, or 0.7:1 to 0.7:6, or 0.7:1 to 0.7:4, or0.7:1 to 0.7:2.5, or 0.7:1 to 2:1.

In the process of the present invention the molar ratio of homogeneousacid catalyst to formaldehyde (homogeneous acid catalyst:formaldehyde)fed to the hydrocarboxylation zone can vary over a considerable range.Examples include feeding at a homogeneous acid catalsyt:formaldehyde offrom 0.001:1 to 1:1, or 0.001:1 to 0.5:1, or 0.001:1 to 0.2:1, or0.001:1 to 0.1:1, or 0.001:1 to 0.07:1, or 0.001:1 to 0.055:1, or 0.01:1to 1:1, or 0.01:1 to 0.5:1, or 0.01:1 to 0.2:1, or 0.01:1 to 0.1:1, or0.01:1 to 0.07:1, or 0.01:1 to 0.05:1 or 0.02:1 to 1:1, or 0.02:1 to0.5:1, or 0.02:1 to 0.2:1, or 0.02:1 to 0.1:1, or 0.02:1 to 0.07:1, or0.02:1 to 0.05:1.

The hydrocarboxylation process can be carried out by feeding carbonmonoxide to a reaction mixture comprising aqueous formaldehyde and ahomogenous acid catalyst. The carbon monoxide typically is supplied tothe reaction mixture in sufficient excess to insure an adequate supplythereof for absorption by the formaldehyde and to retard side reactionssuch as, for example, the decomposition of the formaldehyde to carbonmonoxide and hydrogen or other products. The amount of carbon monoxideuseful for the carbonylation reaction ranges from a molar ratio of 1:1to 1, 000:1 or 1:1 to 100:1 or 1:1 to 20:1 or 1:1 to 10:1 or 2:1 to 20:1or 2:1 to 10:1 of carbon monoxide to formaldehyde or formaldehydeequivalents.

The composition of the carbon monoxide stream required forhydrocarboxylation may comprise carbon monoxide, hydrogen, and carbondioxide. For example, the carbon monoxide may be supplied insubstantially pure form or as a mixture with other gases such as, forexample, hydrogen, carbon dioxide, methane, nitrogen, noble gases (e.g.,helium and argon), and the like. For example, the carbon monoxide neednot be of high purity and may contain from 1% by volume to 99% by volumecarbon monoxide. The remainder of the gas mixture may include such gasesas, for example, nitrogen, hydrogen, water, carbon dioxide, noble gases,and paraffinic hydrocarbons having from one to four carbon atoms. Inorder to reduce compression costs, it is desirable for the carbonmonoxide stream to comprise at least 95 mole % carbon monoxide, morepreferably at least 99 mole %.

The carbon monoxide may be obtained from typical sources that are wellknown in the art. For example, the carbon monoxide may be provided byany of a number of methods known in the art including steam or carbondioxide reforming of carbonaceous materials such as natural gas orpetroleum derivatives; partial oxidation or gasification of carbonaceousmaterials, such as petroleum residuum, bituminous, sub bituminous, andanthracitic coals and cokes; lignite; oil shale; oil sands; peat;biomass; petroleum refining residues of cokes; and the like. Forexample, the carbon monoxide may be provided to the reaction mixture asa component of synthesis gas or “syngas”, comprising carbon dioxide,carbon monoxide, and hydrogen.

The hydrocarboxylation process can be conducted under continuous,semi-continuous, and batch modes of operation and may utilize a varietyof reactor types. Examples of suitable reactor types include, but arenot limited to, stirred tank, continuous stirred tank, tower, andtubular reactors. A typical temperature range for the hydrocarboxylationreaction is 110 to 220° C. Other examples of the temperature range arefrom 110 to 210° C., 110 to 200° C., 110 to 190° C., 120 to 220° C., 120to 210° C., 120 to 200° C., 140 to 220° C., 140 to 210° C., or 150 to210° C. Examples of pressure ranges for the hydrocarboxylation reactionare 35 to 250 bar gauge, 35 to 200 bar gauge, and 60 to 200 bar gauge.In one example of the process, carbon monoxide, aqueous formaldehydecomprising 35 weight percent to 85 weight percent formaldehyde, based onthe total weight of the aqueous formaldehyde, a homogeneous acidcatalyst, and carboxylic acid are fed at a molar ratio of carbonmonoxide to formaldehyde ranging from 1:1 to 10:1, and thehydrocarboxylation reaction zone is operated at a pressure of from 35bar gauge to 200 bar gauge and a temperature of from 120° C. to 220° C.

The hydrocarboxylation reactants may be introduced separately or in anysequence or combination to the hydrocarboxylation reaction zone. Inaddition, one or more reactants may be introduced at different locationsin the reactor. For example, in a continuously operated process, theaddition of water or formaldehyde may be staged throughout the reactor.In some cases, it may be desirable to recirculate a portion of thereaction media to the reactor to act as a liquid reaction media for thenext synthesis. In order to reduce by-product formation, it is desirableto set the residence time in the hydrocarboxylation reaction zone togive an outlet formaldehyde concentration of 5 weight percent or less.In addition to glycolic acid, the hydrocarboxylation process typicallyproduces glycolic acid oligomers, water, and unreacted formaldehyde.When carboxylic acids are present, the hydrocarboxylation processtypically also produces esters of glycolic and carboxylic acids.

In the process of the present invention, an effluent comprising thehomogeneous acid catalyst and the esters of glycolic and carboxylicacids is produced in the hydrocarboxylation reaction zone. The esters ofglycolic and carboxylic acids are produced by the reaction of acarboxylic acid with the hydroxyl end of glycolic acid and/or itsoligomers. In one example, the esters of glycolic and carboxylic acidare selected from the esters of glycolic and propionic acid, the estersof glycolic and n-butyric acid, the esters of glycolic and i-butyricacid, the esters of glycolic and 2-methyl butyric acid, the esters ofglycolic and n-valeric acid, the esters of glycolic and i-valeric acid,or mixtures thereof. In another example, the esters of glycolic andcarboxylic acids comprise 2-propionoxyacetic acid and/or(2′-(propionyloxy)acetoxyacetic acid. In another example, the esters ofglycolic and carboxylic acids comprise 2-valeryloxyacetic acid,(2′-valeryloxy)acetoxyacetic acid, and/or[2′-(2″-valeryloxy)acetoxy]acetoxyacetic acid.

In the process of the present invention, the homogeneous acid catalystis recovered by extracting the effluent with a first hydrophilic solventwith the homogeneous acid catalyst partitioning to the first aqueousextract. In one example, the first hydrophilic solvent comprises water.In another example, the first hydrophilic solvent comprises water andglycolic acid. In another example, the first hydrophilic solventcomprises 10 weight percent to 100 weight percent water and 0 weightpercent to 90 weight percent glycolic acid, each on a total firsthydrophilic solvent weight basis. Other examples include the firsthydrophilic solvent comprising 15 weight percent to 100 weight percentwater and 0 weight percent to 85 weight percent glycolic acid; 20 weightpercent to 100 weight percent water and 0 weight percent to 80 weightpercent glycolic acid; 20 weight percent to 90 weight percent water and10 weight percent to 80 weight percent glycolic acid; or 20 weightpercent to 80 weight percent water and 20 weight percent to 80 weightpercent glycolic acid.

The process of the present invention forms a first aqueous extract phasecomprising a major amount of the homogeneous acid catalyst and a minoramount of the esters of glycolic and carboxylic acids contained in theeffluent. In an aspect of the invention, greater than 90 weight percentof the homogeneous acid catalyst contained in the effluent is recoveredin the first aqueous extract phase. In another aspect, greater than 95weight percent, greater than 98 weight percent, greater than 99 weightpercent, greater than 99.5 weight percent, or greater than 99.9 weightpercent of the homogeneous acid catalyst contained in the effluent isrecovered in the first aqueous extract phase.

The process of the present invention forms a first organic raffinatephase comprising a major amount of the esters of glycolic and carboxylicacids and a minor amount of the homogeneous acid catalyst. In an aspectof the invention greater than 80 weight percent of the esters ofglycolic and carboxylic acids contained in the effluent are recovered inthe first organic raffinate phase. In another aspect, greater than 90weight percent, greater than 95 weight percent, or greater than 98weight percent, or greater than 99 weight percent, or greater than 99.5weight percent of the esters of glycolic and carboxylic acids containedin the effluent is recovered in the first organic raffinate phase. Inanother aspect, greater than 90 weight percent of the esters of glycolicand carboxylic acids are recovered in the first organic raffinate phaseand greater than 95 weight percent of the homogeneous acid catalyst isrecovered in the first aqueous extract phase.

Extracting the effluent can be carried out by any means known in the artto intimately contact two immiscible liquid phases and to separate theresulting phases after the extraction procedure. For example, theextraction can be carried out using columns, centrifuges,mixer-settlers, and miscellaneous devices. Some representative examplesof extractors include unagitated columns (e.g., spray, baffle tray andpacked, perforated plate), agitated columns (e.g., pulsed, rotaryagitated, and reciprocating plate), mixer-settlers (e.g., pump-settler,static mixer-settler, and agitated mixer-settler), centrifugalextractors (e.g., those produced by Robatel, Luwesta, deLaval, DorrOliver, Bird, CINC, and Podbielniak), and other miscellaneous extractors(e.g., emulsion phase contactor, electrically enhanced extractors, andmembrane extractors). A description of these devices can be found in the“Handbook of Solvent Extraction”, Krieger Publishing Company, Malabar,Fla., 1991, pp. 275-501. The various types of extractors may be usedalone or in any combination.

The extraction may be conducted in one or more stages. The number ofextraction stages can be selected in consideration of capital costs,achieving high extraction efficiency, ease of operability, and thestability of the hydrolyzed mixture and extraction solvents to theextraction conditions. The extraction also can be conducted in a batchor continuous mode of operation. In a continuous mode, the extractionmay be carried out in a co-current, a counter-current manner, or as afractional extraction in which multiple solvents and/or solvent feedpoints are used to help facilitate the separation. The extractionprocess also can be conducted in a plurality of separation zones thatcan be in series or in parallel.

The extraction typically can be carried out at a temperature of 10 to120° C. For example, the extraction can be conducted at a temperature of30 to 80° C. The desired temperature range may be constrained further bythe boiling point of the extractant components or water. Generally, itis undesirable to operate the extraction under conditions where theextractant boils. In one aspect, the extractor can be operated toestablish a temperature gradient across the extractor in order toimprove the mass transfer kinetics or decantation rates. In anotheraspect, the extractor may be operated under sufficient pressure toprevent boiling.

In an aspect of the invention, the effluent is extracted in a continuouscounter-current extractor. The first hydrophilic solvent is fed to theextractor at a location higher than the feed location of the effluent.The first hydrophilic solvent moves down the counter-current extractorto form a first aqueous extract phase exiting the bottom of theextractor and comprising a major amount of the homogeneous acid catalystand a minor amount of the esters of glycolic and carboxylic acidscontained in the effluent. The effluent moves up the counter-currentextractor to form a first organic raffinate phase exiting the top of theextractor and comprising a major amount of the esters of glycolic andcarboxylic acids and a minor amount of the homogeneous acid catalystcontained in the effluent. In an aspect of the invention the feed ratioof the first hydrophilic solvent to the effluent on a weight basesranges from 0.1:1 to 20:1, or 0.1:1 to 10:1, or 0.1:1 to 5:1, or 0.1:1to 4:1, or 0.5:1 to 20:1, or 0.5:1 to 10:1, or 0.5:1 to 5:1, or 0.5:1 to4:1, or 1:1 to 10:1, or 1:1 to 5:1, or 1:1 to 4:1.

In another aspect of the invention, the first hydrophilic solventcomprises 15 weight percent to 100 weight percent water and 0 weightpercent to 85 weight percent glycolic acid, each on a total firsthydrophilic solvent weight basis, and the extracting of the effluentoccurs further with a first hydrophobic solvent selected from at leastone of the group consisting of hydrocarbons having from 6 to 20 carbonatoms and ethers having from 4 to 20 carbon atoms thereof. In anotherexample, the first hydrophobic solvent is selected from at least one ofthe group consisting of hexane, cyclohexane, heptane, octane, decane,benzene, toluene, xylene, isoparaffinic mixed hydrocarbons having aboiling range between 90 and 325° C., methyl naphthalene, diethyl ether,dipropyl ether, diisopropyl ether, dibutyl ethers, methyl tertiary-butylether, and methyl tertiary-amyl ether. In another example, the firsthydrophobic solvent is selected from at least one of the groupconsisting of heptane, hexane, toluene, and methyl tertiary-butyl ether.In one aspect, the first hydrophobic solvent is added directly to theeffluent.

The effluent and first hydrophilic solvent can be contacted byfractional extraction methods such as, for example, by fractionalcounter-current extraction. As used herein, the term “fractionalcounter-current extraction” is intended to include, but is not limitedto, a method for separating a feed stream, e.g., effluent, containingtwo or more substances by charging the feed stream to a counter-currentextraction process between the points where two immiscible solvents arecharged to the extraction process. The two immiscible solvents should beimmiscible over the entire temperature range of the extraction process.This method is sometimes referred to as “double solvent extraction.”Fractional counter-current extraction can involve the use of a cascadeof stages, extracting solvents and solution to be extracted entering atopposite ends of the cascade with the feed phase and hydrophobicextractant phase flowing counter-currently. Some example fractionalcounter-current extraction configurations may be found in Treybal,Liquid Extraction, 2nd Edition, McGraw-Hill Book Company, New York.1963, pp. 275-276.

In an aspect of the invention, the effluent is extracted in a continuousfractional counter-current extractor. The first hydrophilic solvent isfed to the extractor at a location higher than the feed location of theeffluent. A first hydrophobic solvent is fed to the extractor at alocation lower than the effluent. In an aspect of the invention the feedratio of the first hydrophilic solvent to the effluent on a weight basisranges from 0.1:1 to 20:1, or 0.5:1 to 20:1, or 1:1 to 10:1, or 1:1 to5:1 and the feed ratio of the first hydrophobic solvent to the effluenton a weight basis ranges from 0.01:1 to 5:1, or 0.05:1 to 2:1, or 0.1:1to 1.5:1, or 0.1:1 to 0.8:1. In one example, the first hydrophobicsolvent is selected from at least one of the group consisting ofhydrocarbons having from 6 to 20 carbon atoms and ethers having from 4to 20 carbon atoms. In another example, the first hydrophobic solvent isselected from at least one of the group consisting of hexane,cyclohexane, heptane, octane, decane, benzene, toluene, xylene,isoparaffinic mixed hydrocarbons having a boiling range between 90 and325° C., methyl naphthalene, diethyl ether, dipropyl ether, diisopropylether, dibutyl ethers, methyl tertiary-butyl ether, and methyltertiary-amyl ether. In another example, the first hydrophobic solventis selected from at least one of the group consisting of heptane,hexane, toluene, and methyl tertiary-butyl ether.

In the process of the present invention, the extracting of the effluentresults in a first aqueous extract phase comprising a major amount ofthe homogeneous acid catalyst and a minor amount of the esters ofglycolic and carboxylic acids contained in the effluent and a firstorganic raffinate phase comprising a major amount of the esters ofglycolic and carboxylic acids and a minor amount of the homogeneous acidcatalyst contained in the effluent. The first aqueous extract phase andthe first organic raffinate phase may be separated by any phaseseparation technology known in the art. The phase separation techniquescan be accomplished in the extractor or in a separate liquid-liquidseparation device. Suitable liquid-liquid separation devices include,but are not limited to, coalescers, cyclones and centrifuges. Typicalequipment that can be used for liquid-liquid phase separation devicesare described in the Handbook of Separation process Technology, ISBN0-471-89558-X, John Wiley & Sons, Inc., 1987.

In the process of the present invention, the first aqueous extract phasecomprising a major amount of the homogeneous acid catalyst may berecycled to step (A). The feeding of a homogeneous acid catalyst to thehydrocarboxylation reaction zone may occur as a mixture comprising freshhomogeneous acid catalyst and the first aqueous extract phase, or anyfresh homogeneous acid catalyst may be fed separately from the firstaqueous extract phase. The first aqueous extract phase may proceeddirectly from the phase separating of step (D) to the feeding to ahydrocarboxylation reaction zone of step (A) or it may undergoprocessing steps, such as concentrating the homogeneous acid catalyst,between the separating of step (D) and the feeding of step (A).

In the process of the present invention, when a first hydrophobicsolvent is either added directly to the effluent or used in a fractionalextraction, the first hydrophobic solvent can be separated from theesters of glycolic and carboxylic acids contained in the first organicraffinate phase and the first hydrophobic solvent can be recycled tostep (B). This recovery of the first hydrophobic solvent and recycle tothe extracting of step (B) may occur before or after the hydrolyzing ofstep (E) of the first organic raffinate phase described below.

The process of the present invention may further comprises (E)hydrolyzing the first organic raffinate phase to produce a hydrolyzedmixture comprising glycolic acid and the carboxylic acid; (F) recoveringthe carboxylic acid from the hydrolyzed mixture by extracting thehydrolyzed mixture with a second hydrophobic solvent selected from atleast one of the group consisting of esters having from 4 to 20 carbonatoms, ethers having from 4 to 20 carbon atoms, ketones having from 4 to20 carbon atoms, and hydrocarbons having from 6 to 20 carbon atoms toform a second aqueous raffinate phase comprising a major amount of theglycolic acid contained in the hydrolyzed mixture and a second organicextract phase comprising a major amount of the carboxylic acid containedin the hydrolyzed mixture; (G) separating the second aqueous raffinatephase and the second organic extract phase; and (H) separating thesecond organic extract phase into the second hydrophobic solvent and thecarboxylic acid, recycling the second hydrophobic solvent to step (F),and recycling the carboxylic acid to step (A).

The process of the present invention may comprise step (E) hydrolyzingthe first organic raffinate phase to produce a hydrolyzed mixturecomprising glycolic acid and the carboxylic acid. The first organicraffinate phase may be hydrolyzed by means known to one skilled in theart. Typically, water will be added to the first organic raffinate phasein an excess of the amount needed to react with the esters of glycolicand carboxylic acids to produce a hydrolyzed mixture comprising glycolicacid and the carboxylic acid. For example, when propionic acid is thecarboxylic acid, the effluent comprises esters of glycolic andcarboxylic acids which include, but are not limited to,2-propionoxyacetic acid and (2′-propionyloxy)acetoxyacetic acid. Theglycolic acid oligomers react with water to form glycolic acid and the2-propionoxyacetic acid and (2′-propionyloxy)acetoxyacetic acid reactwith water to form propionic acid and glycolic acid. In one example thehydrolyzed mixture comprises glycolic acid and at least one carboxylicacid selected from propionic acid, n-butyric acid, i-butyric acid,2-methyl butyric acid, n-valeric acid, and i-valeric acid. In anotherexample, the hydrolyzed mixture comprises glycolic acid and propionicacid. In another example, the hydrolyzed mixture comprises glycolic acidand at least one carboxylic acid selected from 2-methyl butyric acid,n-valeric acid, and i-valeric acid. In another example, the hydrolyzedmixture comprises glycolic acid and valeric acid.

The composition of the hydrolyzed mixture can vary. While an increase inthe amount of water may improve hydrolysis rates, the additional watermust be separated from the glycolic acid. In one example, the molarratio of water to glycolic acid in the resulting hydrolyzed mixture(water:glycolic acid) is from 1:1 to 15:1. Other examples ofwater:glycolic acid are from 1:1 to 8:1, or 1:1 to 6:1, or 1.5:1 to15:1, or 1.5:1 to 8:1, or 1.5:1 to 6:1 or 2:1 to 15:1, or 2:1 to 8:1, or2:1 to 6:1.

The process of the present invention may comprise step (F) recoveringthe carboxylic acid from the hydrolyzed mixture by extracting thehydrolyzed mixture with a second hydrophobic solvent. The carboxylicacid is recovered by extracting the hydrolyzed mixture with a secondhydrophobic solvent with the glycolic acid partitioning to the secondaqueous raffinate. The second hydrophobic solvent can be selected fromat least one of the group consisting of esters having from 4 to 20carbon atoms, ethers having from 4 to 20 carbon atoms, and hydrocarbonshaving from 6 to 20 carbon atoms. In one aspect of the invention, thehydrophobic solvent comprises ethyl acetate, n-propyl acetate, i-propylacetate, n-butyl acetate, i-butyl acetate, s-butyl acetate, methylbenzoate, i-butyl isobutyrate, 2-ethylhexyl acetate, cyclohexyl acetate,methyl propionate, ethyl propionate, n-propyl propionate, i-propylpropionate, i-butyl propionate, n-butyl propionate, s-butyl propionate,diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ethers, methyltertiary-butyl ether, methyl tertiary-amyl ether, methyl ethyl ketone,methyl i-butyl ketone, methyl i-propyl ketone, methyl propyl ketone,dibutyl ketone, diisobutyl ketone, isophorone,3,3,5-trimethylcyclohexanone, cyclohexanone, 2-heptanone,methyl-iso-amyl ketone, diethyl ketone, 5-ethyl 2-nonanone, diamylketone, diisoamyl ketone, hexanes, heptane, toluene, or mixturesthereof. In another aspect of the invention, the hydrophobic solventcomprises n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butylacetate, s-butyl acetate, methyl propionate, ethyl propionate, i-propylpropionate, methyl tertiary-butyl ether, methyl i-butyl ketone, methyli-propyl ketone, methyl propyl ketone, toluene, or mixtures thereof. Inyet another aspect of the invention, the hydrophobic solvent comprisesn-propyl acetate, i-propyl acetate, methyl propionate, ethyl propionate,i-propyl propionate, methyl tertiary-butyl ether, methyl i-butyl ketone,or mixtures thereof.

The process of the present invention forms a second aqueous raffinatephase comprising a major amount of glycolic acid and a minor amount ofcarboxylic acid contained in the hydrolyzed mixture. In an aspect of theinvention, greater than 80 weight percent of the glycolic acid in thehydrolyzed mixture is recovered in the second aqueous raffinate phase.In another aspect, greater than 90 weight percent, greater than 95weight percent, greater than 98 weight percent, greater than 99 weightpercent, or greater than 99.5 weight percent of the glycolic acid in thehydrolyzed mixture is recovered in the second aqueous raffinate phase.

The process of the present invention forms a second organic extractphase comprising a major amount of the carboxylic acid and a minoramount of the glycolic acid. In an aspect of the invention greater than90 weight percent of the carboxylic acid in the hydrolyzed mixture isrecovered in the second organic extract phase. In another aspect,greater than 95 weight percent, greater than 98 weight percent, orgreater than 99 weight percent, or greater than 99.5 weight percent, orgreater than 99.9 weight percent of the carboxylic acid in thehydrolyzed mixture is recovered in the second organic extract phase.

Extracting the hydrolyzed mixture can be carried out by any means knownin the art to intimately contact two immiscible liquid phases and toseparate the resulting phases after the extraction procedure asdescribed herein above.

In an aspect of the process of the invention, the hydrolyzed mixture isextracted in a continuous counter-current extractor. The secondhydrophobic solvent is fed to the extractor at a location lower than thefeed location of the hydrolyzed mixture. The second hydrophobic solventmoves up the counter-current extractor to form a second organic extractphase exiting the top of the extractor and comprising a major amount ofthe carboxylic acid and a minor amount of the glycolic acid contained inthe hydrolyzed mixture. The hydrolyzed mixture moves down thecounter-current extractor to form a second aqueous raffinate phaseexiting the bottom of the extractor and comprising a major amount of theglycolic acid and a minor amount of the carboxylic acid contained in thehydrolyzed mixture. In an aspect of the invention the feed ratio of thesecond hydrophobic solvent to the hydrolyzed mixture on a weight basisranges from 0.1:1 to 20:1, or 0.1:1 to 10:1, or 0.1:1 to 5:1, or 0.1:1to 4:1, or 0.5:1 to 20:1, or 0.5:1 to 10:1, or 0.5:1 to 5:1, or 0.5:1 to4:1, or 1:1 to 10:1, or 1:1 to 5:1, or 1:1 to 4:1.

In an aspect of the process of the invention, the hydrolyzed mixture isextracted in a continuous fractional counter-current extractor. Thesecond hydrophobic solvent is fed to the extractor at a location lowerthan the feed location of the hydrolyzed mixture. A second hydrophilicsolvent is fed to the extractor at a location higher than the hydrolyzedmixture. In an aspect of the invention the feed ratio of the secondhydrophobic solvent to the hydrolyzed mixture on a weight basis rangesfrom 0.5:1 to 20:1, or 1:1 to 10:1, or 1:1 to 5:1 and the feed ratio ofthe second hydrophilic solvent to the hydrolyzed mixture on a weightbasis ranges from 0.05:1 to 2:1, or 0.1:1 to 1.5:1, or 0.1:1 to 0.8:1.In one example, the second hydrophilic solvent comprises water. Inanother example, the second hydrophilic solvent comprises water andethylene glycol. In another example, the second hydrophilic solventcomprises 50 weight percent to 100 weight percent water and 0 weightpercent to 50 weight percent ethylene glycol, each on a total secondhydrophilic solvent weight basis.

In one example, the first hydrophobic solvent and the second hydrophobicsolvent are the same.

In the process of the present invention, the extracting of thehydrolyzed mixture results in a second aqueous raffinate phasecomprising a major amount of the glycolic acid and a minor amount of thecarboxylic acid contained in the hydrolyzed mixture and a second organicextract phase comprising a major amount of the carboxylic acid and aminor amount of the glycolic acid contained in the hydrolyzed mixture.The second aqueous raffinate phase and the second organic extract phasemay be separated by any phase separation technology known in the art asdescribed herein above.

One aspect of the process of the invention further includes (H)separating the second organic extract phase into the second hydrophobicsolvent and the carboxylic acid, recycling the second hydrophobicsolvent to step (F), and recycling the carboxylic acid to step (A). Thesecond hydrophobic solvent and carboxylic acid can be separated by anymeans known to one skilled in the art. Examples include by distillationand extraction. In one example, the second hydrophobic solvent has alower boiling point than the carboxylic acid and the two components areseparated via distillation. The second hydrophobic solvent is recoveredas the distillate product and recycled for extracting in step (F) andthe carboxylic acid is the bottoms product and recycled to thehydrocarboxylation reaction zone in step (A).

One aspect of the process of the present invention further includes (I)reacting a first ethylene glycol with the second aqueous raffinate phasewhile simultaneously removing water to produce an esterificationeffluent comprising glycolate ester oligomers and glycolic acidoligomers and an overhead stream comprising water; and (J) reactinghydrogen with the esterification effluent to produce a second ethyleneglycol, separating the second ethylene glycol into a product ethyleneglycol and the first ethylene glycol, and recycling the first ethyleneglycol to step (I). The reaction between the first ethylene glycol andthe glycolic acid of the second aqueous raffinate phase and simultaneousremoval of water can be conducted under standard esterificationconditions known to persons skilled in the art. Part of the water in thesecond aqueous raffinate phase can be removed prior to esterification.For example, the esterification can be achieved by adding hot ethyleneglycol to the second aqueous raffinate phase and removing water formedduring esterification until sufficient water is removed and anesterification effluent comprising glycolate ester oligomers andglycolic acid oligomers is formed. Typically excess ethylene glycol isused to ensure complete esterification. Examples of mole ratios ofethylene glycol to glycolic acid vary from 1.5:1 to 10:1 or 2:1 to 6:1.Representative conditions for esterification include at a temperature offrom 150 to 250° C., preferably from 170 to 220° C., and a pressure offrom 1 bara to 8 bara, preferably from 1 bara to 5 bara.

The esterification effluent can be hydrogenated to produce ethyleneglycol by contacting the glycolate ester oligomers and glycolic acidoligomers with hydrogen in the presence of a suitable hydrogenationcatalyst. The hydrogenation reaction can be conducted in the liquid orthe gas phase using known processes. Typically, glycolate esteroligomers and glycolic acid oligomers are contacted with hydrogen underpressure in the presence of a catalyst effective for hydrogenation attemperatures from 150 to 300° C. Additional examples of temperaturesranges are from 200 to 250° C. Examples of typical pressure ranges arefrom 35 bara to 350 bara and 70 bara to 140 bara. Considerable latitudein the temperature and pressure of hydrogenation is possible dependingupon the use and choice of hydrogenation catalyst and whether theprocess is conducted in the liquid or gas phase.

The hydrogenation catalyst may comprise any metal or combination ofmetals effective for the hydrogenation of esters to alcohols. Typicalhydrogenation catalysts include, but are not limited to, at least onemetal selected from Groups 8, 9, 10 of the Periodic Table of theElements (1984 Revision by IUPAC), and copper. In addition, thehydrogenation catalyst may comprise at least one additional metalpromoter selected from chromium, magnesium, barium, sodium, nickel,silver, lithium, potassium, cesium, zinc, cobalt, and gold. The term“metal”, as used herein in the context of hydrogenation catalysts, isunderstood to include metals in their elemental form and compoundsthereof such as, for example, metal oxides, salts, and complexes withorganic ligands. For example, the hydrogenation catalyst can comprise aRaney nickel or a metal oxide. Typical metal oxide catalysts include,for example, copper chromite, copper oxide, or copper oxide incombination with the oxide of magnesium, barium, sodium, nickel, silver,lithium, potassium, cesium, zinc, cobalt and the like or mixturesthereof. In another example, the hydrogenation catalyst can comprisecobalt metal in combination with zinc and copper oxides.

The esterification effluent may be purified prior to hydrogenation ormay proceed directly to the hydrogenation reaction. The hydrogenationreaction produces a second ethylene glycol. The second ethylene glycolmay or may not be further purified before separation into a productethylene glycol and a first ethylene glycol which is recycled toesterification step (I).

The present invention provides in a second embodiment a process for thepreparation of glycolic acid, comprising

-   -   (A) feeding carbon monoxide, aqueous formaldehyde, a homogeneous        acid catalyst, and a carboxylic acid selected from at least one        of the group consisting of propionic acid, n-butyric acid,        i-butyric acid, 2-methyl butyric acid, n-valeric acid, and        i-valeric acid to a hydrocarboxylation reaction zone to produce        an effluent comprising the homogeneous catalyst and esters of        glycolic and carboxylic acids;    -   (B) recovering the homogeneous acid catalyst from the effluent        by extracting the effluent with a hydrophilic solvent comprising        15 weight percent to 100 weight percent water and 0 weight        percent to 85 weight percent of glycolic acid, each on a total        hydrophilic solvent weight basis, and optionally with a first        hydrophobic solvent selected from at least one of the group        consisting of hexane, cyclohexane, heptane, octane, decane,        benzene, toluene, xylene, isoparaffinic mixed hydrocarbons        having a boiling range between 90 and 325° C., methyl        naphthalene, diethyl ether, dipropyl ether, diisopropyl ether,        dibutyl ether, methyl tertiary-butyl ether, and methyl        tertiary-amyl ether to form a first aqueous extract phase        comprising a major amount of the homogeneous acid catalyst        contained in the effluent and a first organic raffinate phase        comprising a major amount of the esters of glycolic and        carboxylic acids contained in the effluent;    -   (C) separating the first organic raffinate phase and the first        aqueous extract phase; and    -   (D) recycling the first aqueous extract phase to step (A).

The examples of the first embodiment regarding aqueous formaldehyde,homogeneous acid catalyst, carboxylic acid, molar ratio of carboxylicacid to formaldehyde, molar ratio of homogeneous acid catalyst toformaldehyde, carbon monoxide, hydrocarboxylation reaction zone processconditions, esters of glycolic and carboxylic acids, hydrolyzing andhydrolyzed mixture composition, extraction, first and second hydrophobicsolvent and first and second hydrophilic solvent, as well as feed ratiosof each solvent to the effluent and hydrolyzed mixture on a weightbasis, separation of the first and second extracts and first and secondraffinates, separation of the homogenous acid catalyst from the effluentand recycle of the homogeneous acid catalyst to the hydrocarboxylationreaction zone, separation and recycle of the carboxylic acid and secondhydrophobic solvent, esterification of the glycolic acid andhydrogenation of the glycolate ester oligomers and glycolic acidoligomers to produce ethylene glycol apply to the second embodiment.

For example, the process of the invention includes an aspect wherein thefeeding of the carboxylic acid, homogeneous acid catalyst, and aqueousformaldehyde in step (A) occurs at a molar ratio of carboxylicacid:formaldehyde of from 0.5:1 to 4:1 or 0.5:1 to 2.5:1 and at a molarratio of homogenous acid catalyst:formaldehyde of from 0.01:1 to 0.07:1.In another example the extraction occurs with a first hydrophobicsolvent selected from at least one of the group consisting of hexane,heptane, toluene, xylene, and methyl tertiary-butyl ether. In anotherexample, the carboxylic acid is selected from at least one of the groupconsisting of 2-methyl butyric acid, n-valeric acid, and i-valeric acid.In another example, the carboxylic acid comprises n-valeric acid.

In another example, greater than 90 weight percent of the esters ofglycolic and carboxylic acids are recovered in the first organicraffinate phase and greater than 95 weight percent of the homogenousacid catalyst is recovered in the first aqueous extract phase. Inanother example, the extracting of step (B) occurs in a continuouscounter-current extractor, wherein the first aqueous extract phase exitsthe bottom of the extractor and the first organic raffinate phase exitsthe top of the extractor, the first hydrophilic solvent is fed to theextractor above the effluent, and the feed ratio of the firsthydrophilic solvent to the effluent ranges from 0.5:1 to 4:1 on a weightbasis. Additionally, a first hydrophobic solvent can be fed to theextractor below the effluent, wherein the feed ratio of the firsthydrophobic solvent to the effluent ranges from 0.01:1 to 5:1 on aweight basis, and the feed ratio of the first hydrophilic solvent to theeffluent ranges from 0.5:1 to 4:1 on a weight basis.

In another example of the process of the present invention, the aqueousformaldehyde comprises 35 weight percent to 85 weight percentformaldehyde, based on the total weight of the aqueous formaldehyde, themolar ratio of carbon monoxide to formaldehyde ranges from 1:1 to 10:1,and the hydrocarboxylation reaction zone is operated at a pressure offrom 35 bar gauge to 200 bar gauge and a temperature of from 120° C. to220° C.

In yet another example, the above process further comprises (E)hydrolyzing the first organic raffinate phase to produce a hydrolyzedmixture comprising glycolic acid and the carboxylic acid; (F) recoveringthe carboxylic acid from the hydrolyzed mixture by extracting thehydrolyzed mixture with a second hydrophobic solvent selected from atleast one of the group consisting of n-propyl acetate, i-propyl acetate,n-butyl acetate, i-butyl acetate, s-butyl acetate, methyl propionate,ethyl propionate, i-propyl propionate, methyl tertiary-butyl ether,methyl i-butyl ketone, methyl i-propyl ketone, methyl propyl ketone, andtoluene to form a second aqueous raffinate phase comprising a majoramount of the glycolic acid contained in said hydrolyzed mixture and asecond organic extract phase comprising a major amount of the carboxylicacid contained in the hydrolyzed mixture; (G) separating the secondaqueous raffinate phase and the second organic extract phase; and (H)separating the second organic extract phase into the second hydrophobicsolvent and the carboxylic acid, recycling the second hydrophobicsolvent to step (F), and recycling the carboxylic acid to step (A).

In yet another example, the above process further comprises (I) reactinga first ethylene glycol with the second aqueous raffinate phase whilesimultaneously removing water to produce an esterification effluentcomprising glycolate ester oligomers and glycolic acid oligomers and anoverhead stream comprising water; and (J) reacting hydrogen with theesterification effluent to produce a second ethylene glycol, separatingthe second ethylene glycol into a product ethylene glycol and the firstethylene glycol, recycling the first ethylene glycol to step (I).

FIG. 1 presents a non-limiting embodiment of the instant inventiondescribed herein in detail. In an embodiment of the invention as laidout in FIG. 1, Carbon Monoxide Stream 1, Aqueous Formaldehyde Stream 2,First Aqueous Extract Stream 3 comprising the homogenous acid catalystand Valeric Acid Stream 14 are fed to Hydrocarboxylation Reactor 50.Effluent Stream 4 comprises the esters of glycolic and valeric acidincluding 2-valeryloxyacetic acid, (2′-valeryloxy)acetoxyacetic acid,and/or [2′-(2″-valeryloxy)acetoxy]acetoxyacetic acid. Effluent Stream 4is fed to First Extractor 51 where it is extracted with FirstHydrophilic Solvent Stream 5. First Extractor 51 is shown as afractional extractor with First Hydrophobic Solvent 6 also being fed toFirst Extractor 51. Exiting First Extractor 51 are First Aqueous ExtractPhase 3 which is recycled to Hydrocarboxylation Reactor 50 and FirstOrganic Raffinate Stream 7. FIG. 1 shows First Organic Raffinate Stream7 being fed to Recovery Unit 53 where First Hydrophobic Solvent Stream 6is recovered and recycled to First Extractor 51. Recovered Esters ofGlycolic and Valeric Acids Stream 8 exiting Recovery Unit 53 is fedalong with Water Stream 9 to Hydrolyzer 55. Hydrolyzer 55 is operated atsufficient temperature, pressure, and residence time to produceHydrolyzed Mixture Stream 10 comprising glycolic acid, valeric acid, andwater. Hydrolyzed Mixture Stream 10 is extracted with Second HydrophobicSolvent Stream 11, such as methyl tertiary-butyl ether, in SecondExtractor 60, to produce Second Organic Extract Stream 12 and SecondAqueous Raffinate Stream 13. Organic Extract Stream 12 can be separatedinto Valeric Acid Stream 14 and Second Hydrophobic Solvent Stream 11 inSeparator 70. Separator 70 can be, for example, a distillation column.Valeric Acid Stream 14 is recycled to Hydrocarboxylation Reactor 50 andHydrophobic Solvent Stream 11 is recycled to Extractor 60.

The invention can be further illustrated by the following examples ofpreferred embodiments thereof, although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention.

EXAMPLES

The compounds and abbreviations given in Table 1 are used throughout theExamples section. Structures for each compound are also given.

TABLE 1 Compound Names, Structures, and Abbreviation Name Structure CodeGlycolic Acid

G1 (2- hydroxyacetoxy)- acetic acid

G2 2-(2′- hydroxyacetoxy)- acetoxyacetic acid

G3 2-(2′-(2″- hydroxyacetoxy)- acetoxy) acetoxyacetic acid

G4 Acetic Acid

A2 Acetoxyacetic acid

A2GH Propionic Acid

A3 Propionoxyacetic Acid

A3GH Propionoxyacetic Acid Oligomer

A3Gn H n = 2-4 Valeric Acid

A5 Valeryloxyacetic Acid

A5GH (2′-Valeryloxy)- acetoxyacetic Acid

A5G2 H [2′-(2″- Valeryloxy) acetoxy]- acetoxyacetic Acid

A5G3 H Formaldehyde

F0 Methylene Glycol

F1 Polymethylene glycol

Fn n = 2-10 Formic Acid

A1 Diglycolic Acid

DG 2-Methoxyacetic Acid

MGH Methyl Glycolate

MG Methylene Diacetate

MDA Methylene Dipropionate

MDP

Materials—Acetic and propionic acids (99.5%), nonafluorobutanesulfonicacid and AMBERLYST 36 ion exchange resin were purchased from AldrichChemical Company. AMBERLYST resin, manufactured by Rohm & Hass ChemicalCompany, is crosslinked polystyrene beads that have been sulfonated.AMBERLYST 36D is <1.65% wet with 5.4 meq/g acid capacity and arecommended maximum operating temperature of 150° C. Sulfuric acid waspurchased from J. T. Baker, trifluoromethanesulfonic acid (also known astriflic acid) and bis(trifluoromethylsulfonyl)amide were purchased fromSynQuest Labs, Inc., tetrafluoroethanesulfonic acid was purchased fromDuPont Chemical Company. Paraformaldehyde (90% min) was purchased fromKodak. Solid acid catalysts were received from suppliers as detailedbelow. All chemicals were used as received except as noted below.

Yield—

Ultimately, the hydrocarboxylation process is used to produce glycolicacid. The crude product from a hydrocarboxylation reaction, which takesplace in carboxylic acid, comprises the esters of glycolic andcarboxylic acids. For example, when the carboxylic acid is propionicacid, the crude product comprises methyl glycolate (MG), glycolic acid(G1) and its oligomers (Gn, n=2-5) and 2-propionoxyacetic acid (A3 GH)and its oligomers (A3GnH, n=2-4). When a GC method was used, the yieldof desired products was calculated based upon the total moles ofglycolic acid moiety. The term “glycolic acid moiety,” as used herein,refers to the O—CH₂—CO₂ segment of a molecule, for example, the segmentin glycolic acid, a glycolic acid oligomer, or an ester of glycolic andcarboxylic acids. The glycolic acid moieties divided by the moles offormaldehyde fed gives the yield. When an LC method was used, all of theglycolic acid moieties are converted to glycolic acid by the samplepreparation. The yield was calculated simply as the moles of glycolicacid divided by the moles of formaldehyde fed.

Selectivity—

Selectivities to glycolic acid were calculated as the total moles ofdesired product for GC method as given above or the total moles ofglycolic acid for the HPLC method divided by moles of all productsformed from formaldehyde such as formic acid, methyl glycolate,diglycolic acid, and others.

Gas Chromatography (GC) Method 1. Samples were analyzed using aHewlett-Packard HP-5890 chromatograph equipped with split injectors andFIDs. The injector and detector port temperatures were 250° C. and 300°C., respectively. A DB-5 [(5% phenyl)-methylpolysiloxane] capillarycolumn was employed. Hydrogen was used as the carrier gas with a columnhead pressure of 9 psig and a column flow of 1.6 ml/minute, which gave acarrier gas linear velocity of 43 cm/second. 0.5-μl of the preparedsample solution was injected with a split ratio of 40:1. The columntemperature was programmed as follows: the initial oven temperature wasset at 80° C. and was held for 3 minutes, the oven was then ramped up to280° C. at a rate of 10° C./minute and was held at 280 for 7 minutes.Samples were prepared for gas chromatographic analysis according to thefollowing procedure: 0.1±0.001 g of sample, 200.0 μl ISTD solution (1%by volume of decane in pyridine) and 1.0 ml of BSTFA(N,O-bis(tri-methylsilyl)trifluoroacetamide) with 1% TMSCl(trimethylchlorosilane) were heated in a vial at 80° C. for 30 minutesto ensure complete derivatization. A 0.5-μl sample of this derivatizedsolution was injected for GC analysis.

For a typical crude reaction product, 26 species were identified usingGC/MS. For the example of propionic acid as the carboxylic acid, thedesired products are methyl glycolate (MG), glycolic acid (G1) and itsoligomers (Gn, n=2-5) and 2-propionoxyacetic acid (A3 GH) and itsoligomers (A3GnH, n=2-4). Identified co-products include formic acid(A1), and diglycolic acid (DG). Unreacted starting materials are in theform of free formaldehyde (F0), methylene glycol (F1) and polymethyleneglycol (Fn, n=2-10).

Gas Chromatography (GC) Method 2. The components of samples were firstreacted with BSTFA in the presence of pyridine to the correspondingTMS-derivatives including water, which were then separated andquantified by an internal standard (decane or dodecane) wt % calibratedGC method. The volume ratio of sample to derivatization reagent (BSTFA)and pyridine (containing the internal standard compound) was 0.1 g: 1ml:0.2 ml in a GC vial, which was heated at 80° C. for 30 minutes toensure complete derivatization. The GC method uses a DB-1301 capillarycolumn or equivalent (6% cyanopropylphenyl/94% dimethylpolysiloxanestationary phase, 60 meters×0.32 mm ID×1.0 um film thickness), a splitinjector (at 280° C.), a flame ionization detector (at 300° C.), heliumcarrier gas at a constant linear velocity of 27 cm/sec (a Shimadzu GC2010 or equivalent) or at an initial column head pressure of 17 psig, anoven temperature program of 80° C. initial temp for 6 min, 4° C./mintemp ramp to 150° C. held for 0 min and 10° C./min temp ramp to 290° C.for 17.5 min final hold time. 1 μl of the prepared sample solution wasinjected with a split ratio of 40:1 Analytes include: MeOH, A1, water,heptane, toluene, G1 and higher oligomers, A5 GH and higher oligomers,DG, methyl valerate, and MG.

High Pressure Liquid Chromatography (HPLC) Method 1. Samples wereprepared by pipetting 100 μl of sample into a 10 mL volumetric flask,adding a few mLs of water, ten drops of conc. H₃PO₄, and diluting to themark with water. An aliquot of sample was injected onto an Agilent 1100HPLC instrument for analysis using a BIORAD Fast Acid Analysis Column(100×7.8 mm) at 60° C. The sample is eluted using 10 mM sulfuric acid inwater with a flow rate of 1 mL/min. Glycolic acid was detected at 210 nmon the UV detector. An external standard was used for calibration alongwith a dilution factor in a sequence table. The results are reported asppm using a two-level calibration curve (100 and 1000 ppm) for eachacid.

High Pressure Liquid Chromatography (HPLC) Method 2. Glycolic acidconcentration was quantitatively determined by an Agilent 1100 HPLCusing a Hamilton PRP-X300 exclusion column (250×4.1 mm). Glycolic acidwas detected at 210 nm on the UV detector. Two eluents were used, whereeluent A is 5 mM H₃PO₄ in 1% acetonitrile/99% water and eluent B is 5 mMH₃PO₄ in 10% acetonitrile/90% water. The following gradient was used:100% A for 2 min; ->100% B 5 min; Hold for 3 mins; ->100% A 0.1 mins;equilibrate 4.9 mins for a total run time of 15 minutes. HPLC sampleswere prepared according to the following method. The samples of crudehydrocarboxylation reaction are hydrolyzed and diluted for analysisaccording to the following procedure: 200 mg of sample is weighed into a10 mL volumetric flask, then 0.5 mL of 40% NaOH is added. After 10minutes, 2 mL of water is added and the solution is allowed to sit foranother 10 minutes. The solution is then diluted to the mark with water.A milliliter of this solution is then diluted tenfold before analysis.

High Pressure Liquid Chromatography (HPLC) Method 3. Samples wereanalyzed by liquid chromatography for glycolic acid using ion-exclusionchromatography after samples were subjected to acid hydrolysis inaqueous 25% v/v H₂SO₄ at 80° C. for 30 minutes. The analytes wereseparated on a Hamilton PRP X300 column using a 10 mM H₃PO₄ mobile phasewith a 1-20% v/v acetonitrile gradient. The eluting components weremonitored using a UV detector set at 210 nm and their concentrationscalculated based on calibration using external standards. Formaldehydewas determined by liquid chromatographic separation of the2,4-dinitrophenylhydrazone derivative of formaldehyde and its subsequentdetection by UV at 360 nm. The same acid hydrolysate from the procedureabove was reacted with dinitrophenylhydrazine, then analyzed using aPhenomenex Luna C8 column using a 1:1 water:acetonitrile mobile phaseunder isocratic conditions. The formaldehyde concentration wascalculated based on calibration using external standards.

X-ray method for triflic acid. Reactor effluent and extraction sampleswere analyzed for sulfur using a wavelength dispersive x-rayfluorescence (WDXRF) semi-quantitative application called UNIQUANT™(UQ). UQ affords standardless XRF analysis of samples. The data weremathematically corrected for matrix differences between calibrationstandards and samples as well as absorption and enhancement effects;i.e., inter-element effects. Instrument conditions for sulfur analysiswere: Line, K_(a); kV, 40; mA, 60; Filter, none; Collimator Spacing(mm), 150; Crystal, Ge III-C; Peak Angle (2q), 110.6712; Detector, flow;PHD Lower, 35; PHD Upper, 70; Collimator Mask (mm), 30; Peak time (s),30. Sulfur weight fraction numbers were converted to triflic acid weightequivalents by the factor 4.68 (ratio of molecular weight of triflicacid to that of sulfur).

Example 1

20% W-heteropoly/silica catalyst purchased from Johnson Matthey was usedas received. A 50 mL Hastelloy 276C autoclave was heated with a heatingblock, with temperature control provided by feedback via a thermocouplein the autoclave thermowell. Pure carbon monoxide gas (>99.9%) was fedto the autoclave via a high pressure regulator. The autoclave wascharged with the paraformaldehyde (3.12 g, 0.099 mol), propionic acid(30.74 g, 0.41 mol), 20% W-heteropoly/silica catalyst (1.9 g),assembled, and pressurized with 200 psig of nitrogen and vented. Thispurging procedure was repeated two times. To remove nitrogen from theautoclaves, they were purged with 200 psig of carbon monoxide. Then thereactors were pressurized with 200 psig of carbon monoxide and heatedwith stirring to 140° C. The reactor was then pressurized to 1000 psigcarbon monoxide and the pressure was maintained from the surge tank.After a 2 hour hold time, the reactor was cooled to room temperature andvented. Finally the autoclave was purged with nitrogen and unloaded. Thereaction content was analyzed by GC and/or HPLC. Table 2 gives theyield.

Examples 2-7

Example 1 was repeated using the catalyst and catalyst loading and holdtime given in Table 2. The resulting yields are also given in Table 2.

For Examples 4 and 5, the AMBERLYST catalyst preparation was as follows.The resin was washed up-flow with six bed volumes of ambient temperaturedistilled water over a period of 15 minutes. The washed resins were thendried in a vacuum oven at 109° C. and placed in a desiccator untilneeded.

For Examples 6 and 7 the SMOPEX 101 catalyst preparation was as follows.To 20 g of SMOPEX catalyst, in 250 mL beaker, 50 mL of propionic acidwas added. The catalyst was allowed to sit for 15 min and then filteredusing vacuum filtration. The vacuum was turned off and 20 mL ofpropionic acid was passed through the catalyst. This step was repeatedthree times to ensure that all of the water was washed off of thecatalyst. Finally the solid was dried under house vacuum overnight.

TABLE 2 Hydrocarboxylation of Paraformaldehyde in Propionic AcidCatalyzed by Strongly Acidic Solid Acid Catalysts. loading temp timeyield EX catalyst (wt %) (° C.) (h) (%) 1 20% W-heteropoly/silica 5.1140 2 2.1 2 SiO₂/Al₂O₃ 5 140 2 2.6 3 SAC-13 15 140 3 82.3 4 AMBERLYST 36(5.4 mmol/g) 5.0 140 2 71.1 5 AMBERLYST 36 (5.4 mmol/g) 5.0 140 3 75.7 6SMOPEX 101 (4% crosslinked) 5.0 140 3 61.4 7 SMOPEX 101 (12%crosslinked) 5.0 140 3 69.4

The following examples demonstrate the effect of pressure, temperature,and water content on the batch hydrocarboxylation of paraformaldehyde inpropionic acid using a dry AMBERLYST 36 solid acid catalyst.

Example 8

A 300 ml Hastelloy 276C autoclave was charged with paraformaldehyde(15.99 g, 0.53 mol), dry AMBERLYST 36 catalyst (9.3 g), propionic acid(157.9 g, 2.13 mol), and formic acid (3.8 g). The autoclave was thenassembled and pressurized with 200 psig of N₂ and vented. This purgingprocedure was repeated two times. The autoclave was purged with 200 psigcarbon monoxide in order to remove N₂. The reactor was pressurized withcarbon monoxide to 500 psig and heated with stirring to 100° C. Once thedesired temperature was reached, the reactor was pressurized to 1500psig carbon monoxide and the pressure of the autoclave was maintainedfrom a surge tank. Samples of the reaction were taken over the durationof the experiment at approximately 0.5, 1, 1.5, 2, 2.5, and 3 hours.When the reaction time was complete, the reactor was cooled to roomtemperature and vented. The autoclave was purged with nitrogen and theproduct mixture removed. The samples were analyzed by GC. Thetemperature and pressure; the weight percent paraformaldehyde, propionicacid, and water; and the yield of desired products and selectivity aregiven in Table 3. The concentration of formic acid ranged from 2.2weight percent to 2.4 weight percent.

Examples 9-32

Example 8 was repeated for examples 9-32 with no water, as in Example 8,or water (nominally 4.58 g, 0.5 eq.), or water (nominally 9.12 g, 1.0eq.) with formic acid added at an amount of 2.0 wt % of the chargedcomposition. The feed composition as well as the temperature andpressure of the reactor are as noted in Table 3. The temperature andpressure; the weight percent paraformaldehyde, propionic acid, andwater; and the yield of desired products and selectivity are given inTable 3.

TABLE 3 Hydrocarboxylation of Paraformaldehyde in Propionic AcidCatalyzed by AMBERLYST 36D (4.6-4.8 wt %). Yield of Tem- desired Selec-Pressure perature Feed (wt %) Time products tivity EX (psig) (° C.) F0A3 Water (h) (%) (%) 8 1,500 100 9.0 88.8 0.0 0.5 14 53 1.0 29 68 1.5 4373 2.0 53 79 2.5 64 85 3.0 71 88 9 1,000 100 9.0 88.8 0.0 0.5 25 63 1.042 72 1.5 62 83 2.0 73 99 2.5 81 100 3.0 86 101 10 500 100 9.0 88.8 0.00.5 11 100 1.0 20 99 1.5 27 95 2.0 36 88 2.5 45 84 3.0 53 81 11 1,500100 8.6 84.4 4.9 0.5 2 79 1.0 2 81 1.5 3 83 2.0 10 80 2.5 11 82 3.0 1289 12 1,000 100 8.5 84.4 4.9 0.5 7 84 1.0 7 69 1.5 8 69 2.0 9 68 2.5 1065 3.0 12 66 13 500 100 8.6 84.4 4.9 0.5 5 83 1.0 5 82 1.5 6 91 2.0 1 802.5 7 85 3.0 8 71 14 750 100 8.6 84.4 4.9 0.5 5 78 1.0 6 75 1.5 7 73 2.07 70 2.5 8 70 3.0 9 66 15 750 100 9.0 88.8 0.0 0.5 12 95 1.0 24 92 1.528 96 2.0 37 81 2.5 46 87 3.0 54 85 16 500 100 8.8 86.6 2.5 0.5 7 99 1.08 93 1.5 9 90 2.0 10 86 2.5 13 85 3.0 15 82 17 750 100 8.8 86.6 2.5 0.58 89 1.0 10 96 1.5 13 87 2.0 16 91 2.5 19 83 3.0 23 91 18 1000 100 8.886.6 2.5 0.5 6 102 1.0 7 113 1.5 7 108 2.0 7 104 2.5 9 101 3.0 12 82 191,500 100 8.8 86.6 2.5 0.5 10 80 1.0 13 79 1.5 17 79 2.0 20 80 2.5 24 803.0 28 80 20 1,500 100 9.0 88.8 0.0 0.5 17 94 1.0 31 81 1.5 44 82 2.0 5889 2.5 68 90 3.0 75 92 21 500 100 9.0 88.8 0.0 0.5 9 73 1.0 12 87 1.5 1785 2.0 21 81 2.5 24 81 3.0 28 81 22 1,500 100 8.6 84.4 4.9 0.5 4 27 1.04 28 1.5 5 28 2.0 6 24 2.5 6 24 3.0 7 26 23 500 100 8.5 84.4 4.9 0.5 177 1.0 6 87 1.5 6 80 2.0 6 80 2.5 7 75 3.0 8 76 24 1000 100 8.8 86.6 2.50.5 6 77 1.0 10 82 1.5 12 90 2.0 13 87 2.5 19 90 3.0 21 90 25 500 1409.0 88.8 0.0 0.5 45 81 1.0 63 85 1.5 77 99 2.0 78 104 2.5 78 106 3.0 79108 26 1,500 140 8.6 84.4 4.9 0.5 38 75 1.0 48 78 1.5 59 83 2.0 65 902.5 68 92 3.0 69 92 27 1,000 120 8.6 86.6 2.5 0.5 16 68 1.0 24 70 1.5 3270 2.0 39 86 2.5 48 87 3.0 52 89 28 500 140 8.6 84.4 4.9 0.5 20 63 1.032 65 1.5 40 69 2.0 54 76 2.5 48 79 3.0 52 82 29 1,500 140 9.0 88.8 0.00.5 67 97 1.0 82 100 1.5 75 102 2.0 84 107 2.5 84 108 3.0 84 108 302,000 140 9.0 88.9 0.0 0.5 78 97 1.0 83 100 1.5 84 102 2.0 85 103 2.5 86104 3.0 87 104 31 2,000 140 8.6 84.5 4.9 0.5 38 77 1.0 61 84 1.5 71 872.0 76 89 2.5 77 90 3.0 79 91 32 2,000 140 8.8 86.6 2.5 0.5 60 86 1.0 7291 1.5 78 93 2.0 80 94 2.5 79 95 3.0 80 95

The following examples demonstrate the hydrocarboxylation ofparaformaldehyde using a triflic acid catalyst in acetic, propionic,n-butyric, i-butyric, valeric, and hexanoic acids.

Example 33

A 100 mL zirconium high pressure autoclave was fitted with an impeller,gas inlet tube, sample tube, and thermowell. The autoclave was heatedwith a heating block, with temperature control provided by feedback viaa thermocouple in the autoclave thermowell. Pure carbon monoxide gas(>99.9%) was fed to the autoclave via a high pressure regulator. Triflicacid (0.562 g, 3.7 mmol), acetic acid (30.03 g, 0.5 mol) andparaformaldehyde (3.94 g, 0.125 mol) were added to the autoclave andsealed. The autoclave was secured to the stand and the system was purgedwith carbon monoxide and pressurized to 250 psig carbon monoxide. Thetemperature in the autoclave was increased to 140° C. while stirring at1000 rpm. Upon reaching 140° C., the pressure in the autoclave wasincreased to 1,000 psig carbon monoxide. Once temperature and pressurewere reached, a sample was taken, “time 0.” The pressure and temperaturewere maintained for 4 hours. Subsequent samples of the reaction weretaken at approximately 15, 30, 45, 60, 90, 120, 180 and 240 minutes andanalyzed by HPLC. Results are given in Table 4, in terms of yield ofglycolic acid and selectivity.

Example 34

Example 33 was repeated except that propionic acid (37.04 g, 0.5 mol)was charged to the autoclave in place of acetic acid. Results are givenin Table 4.

Example 35

Example 33 was repeated except that n-butyric acid (44.06 g, 0.5 mol)was charged to the autoclave in place of acetic acid. Results are givenin Table 4.

Example 36

Example 33 was repeated except that i-butyric acid (44.06 g, 0.5 mol)was charged to the autoclave in place of acetic acid. Results are givenin Table 4.

Example 37

Example 33 was repeated except that valeric acid (51.07 g, 0.5 mol) wascharged to the autoclave in place of acetic acid. Results are given inTable 4.

Example 38

Example 33 was repeated except that hexanoic acid (58.08 g, 0.5 mol) wascharged to the autoclave in place of acetic acid. Results are given inTable 4.

TABLE 4 Hydrocarboxylation of Paraformaldehyde in Carboxylic AcidsCatalyzed by Triflic Acid. EX Carboxylic Acid Time (h) Yield (%)Selectivity (%) 33 Acetic Acid 0 14.1 79.2 0.3 45.9 92.0 0.5 84.1 93.50.8 92.8 96.5 1.0 97.2 95.8 1.3 96.5 95.8 1.8 98.9 97.1 3.0 98.3 99.44.0 99.9 98.2 34 Propionic Acid 0 7.5 45.1 0.3 28.1 74.6 0.5 59.9 87.10.8 74.1 89.7 1.0 76.4 90.6 1.5 81.9 92.4 2.4 85.9 94.0 2.8 84.9 94.84.0 83.4 94.2 35 n-butyric acid 0 10.2 74.9 0.3 40.8 87.1 0.5 70.0 94.20.8 90.8 97.5 1.0 89.9 97.2 1.3 97.3 97.9 1.8 101.1 97.6 3.0 104.4 98.34.0 104.1 98.2 36 i-butyric 0 9.8 67.6 0.3 21.7 78.8 0.5 40.1 82.6 0.846.9 84.7 1.0 52.7 86.8 1.5 57.8 88.5 2.4 67.0 92.5 2.8 66.8 92.3 4.065.6 93.3 37 Valeric Acid 0 9.5 64.5 0.3 28.4 72.6 0.5 55.0 87.2 0.869.1 92.2 1.0 82.9 100.0 1.3 94.4 99.5 1.8 96.0 100.0 3.0 99.3 98.5 4.0100.8 100.0 38 Hexanoic Acid 0 7.9 42.2 0.3 20.9 55.0 0.5 41.7 71.4 0.854.5 77.5 1.0 65.0 83.3 1.3 73.9 87.9 1.8 77.9 92.9 3.0 81.8 94.2 4.084.5 97.2

For all extraction examples the partition coefficient for component A isdefined as follows:

${P(A)} = \frac{{Weight}\mspace{14mu} {Percent}\mspace{14mu} A\mspace{14mu} {in}\mspace{14mu} {Hydrophobic}\mspace{14mu} {phase}}{{Weight}\mspace{14mu} {Percent}\mspace{14mu} A\mspace{14mu} {in}\mspace{14mu} {Hydrophilic}\mspace{14mu} {phase}}$

Extraction selectivity between components A and B is defined as:

S(AB)=P(A)/P(B)

Example 39

A first standard aqueous acetic-glycolic acid solution was prepared bymixing glycolic acid, water, and acetic acid. Fifteen grams of thisfirst standard solution was added to a separate glass vial along withfifteen grams of each of the nonpolar solvents listed in Table 5. Asecond standard aqueous propionic-glycolic acid solution was preparedand fifteen grams of this second standard solution was added to aseparate glass vial along with fifteen grams of each of the non polarsolvents listed in Table 5. The contents of each vial were mixedvigorously and allowed to settle and separate into two clear phases. Allexperiments were conducted at room temperature. The phases were analyzedby GC to determine acetic acid, propionic acid, and glycolic acidcompositions. These analytical results were used to calculate partitioncoefficients and extraction selectivities. Results are summarized inTable 5. The partition coefficients and selectivities for propionic acidare higher than the corresponding values for acetic acid, thusillustrating the value of using propionic acid instead of acetic acid asa hydrocarboxylation solvent/reactant.

TABLE 5 Extraction Compositions, Partition Coefficients andSelectivities for Mixtures Containing Acetic Acid and Propionic acid.acid glycolic water solv. P P S Ex. Solvent acid (g) (g) (g) (g) (acid)(glycolic) (acid/glycolic) 39a Toluene acetic 3.6 2.4 9 15 0.08<0.001 >80 39b Heptane acetic 3.6 2.4 9 15 0.02 <0.001 >20 39c methylacetic 3.6 2.4 9 15 0.80 0.14 6 propionate 39d MTBE acetic 3.6 2.4 9 151.00 0.07 14 39e Toluene propionic 3.6 2.4 9 15 0.70 <0.001 >70 39fHeptane propionic 3.6 2.4 9 15 0.10 <0.011 >10 39g methyl propionic 3.62.4 9 15 2.50 0.16 16 propionate 39h MTBE propionic 3.6 2.4 9 15 3.400.09 38

Examples 40-50

These examples illustrate the selective extractive separation ofn-valeric, n-butyric (nHOBu), iso-butyric (iHOBu), and propionic (HOPr)acids from highly concentrated aqueous glycolic acid. Aqueous glycolicacid-water-carboxylic acid mixtures were prepared and added to separateglass vials along with the amount of each hydrophobic solvent as listedin Table 6. The contents of each vial were mixed vigorously and allowedto settle and separate into two clear phases. All experiments wereconducted at room temperature. The phases were analyzed by GC todetermine carboxylic acid and glycolic acid compositions. Theseanalytical results were used to calculate partition coefficients andselectivities. Results are summarized in Table 6.

TABLE 6 Extraction compositions, Partition Coefficients andSelectivities. acid glycolic water solv. P P S Ex. Solvent acid (g) (g)(g) (g) (acid) (glycolic) (acid/glycolic) 40 Toluene n-butyric 10 8 2 105.2 0.035 148.8 41 MTBE n-butyric 10 8 12 15 7.4 0.189 39.4 42 Heptanen-butyric 10 8 2 10 3.4 0.015 220.4 43 Toluene i-butyric 10 8 2 10 7.40.027 271.6 44 MTBE i-butyric 10 8 11 15 8.3 0.176 46.9 45 Heptanei-butyric 10 8 2 10 6.7 0.011 626.6 46 Toluene propionic 10 8 2 10 1.90.056 34.5 47 MTBE propionic 10 8 12 15 2.2 0.341 6.6 48 MIBK propionic10 8 12 15 2.0 0.303 6.6 49 heptane n-valeric 8 6 2 4 8.2 0.0001 5,672.150 toluene n-valeric 8 6 2 4 13.5 0.030 446.6

Examples 51-58

These examples illustrate the effect of glycolic acid content on theextractive separation of n-valeric acid from glycolic acid. Aqueousglycolic acid-water-n-valeric acid mixtures were prepared and added toseparate glass vials along with the amount of toluene or heptane aslisted in Table 7. The contents of each vial were mixed vigorously andallowed to settle and separate into two clear phases. All experimentswere conducted at room temperature. The phases were analyzed by GC todetermine n-valeric acid and glycolic acid compositions. Theseanalytical results were used to calculate partition coefficients andselectivities as shown in Table 7.

TABLE 7 Extraction Compositions, Partition Coefficients andSelectivities. wt. % acid glycolic water solv. P P S Ex. solventglycolic (g) (g) (g) (g) (acid) (glycolic) (acid/glycolic) 51 toluene 758 5.99 2.00 4.00 329 0.44 748.2 52 toluene 50 8.00 4.01 4.01 4.02 6360.31 2,041.3 53 toluene 25 7.98 2.01 6.02 3.99 763 0.18 4,183.8 54toluene 0 7.97 0.00 8.15 4.03 1,319 NA NA 55 heptane 75 8.09 6.06 2.024.04 8.0 0.006 1,419.3 56 heptane 50 8.02 4.05 4.05 4.01 12.4 0.0062,099.0 57 heptane 25 8.11 2.01 6.04 4.04 15.0 0.004 3,767.9 58 heptane0 8.03 0.00 8.02 4.19 18.9 NA NA

Examples 59-62

These examples illustrate the effect of glycolic acid content on theextractive separation of valeric acid from triflic acid and glycolicacid. Aqueous glycolic acid-water-triflic acid mixtures were preparedand added to separate glass vials along with the amount of toluene andvaleric acid as listed in Table 8. The contents of each vial were mixedvigorously and allowed to settle and separate into two clear phases. Allexperiments were conducted at a temperature of 50° C. The phases wereanalyzed by GC and X-ray to determine valeric, triflic acid, andglycolic compositions. These analytical results were used to calculatepartition coefficients and selectivities as shown in Table 8.

TABLE 8 Extraction Compositions, Partition Coefficients andSelectivities of Valeric Acid, Triflic Acid and Glycolic Acid inToluene. Acid glycolic water solv. triflic P P P S S Ex. (g) (g) (g) (g)(g) (acid) (glycolic) (triflic) (acid/glycolic) (acid/triflic) 59 1.070.00 9.72 9.00 0.30 13.7 NA 0.0002 NA 57,499 60 4.00 0.00 7.77 7.99 0.2438.0 NA 0.001 NA 38,376 61 1.02 7.79 1.95 9.02 0.30 2.0 0.001 0.00011,388.1 20,302 62 4.03 6.23 1.56 8.03 0.24 4.2 0.031 0.0012 136.6 3,414

Example 63

A solution rich in esters of glycolic and valeric acids was prepared bymixing 1.45 moles of valeric acid per mole of glycolic acid. Thismixture was heated to reflux under vacuum to remove approximately 0.2grams of water per gram of glycolic acid fed, to give an average degreeof oligomerization of 0.84 ester bonds per mole of glycolic acid (i.e.,mostly A5 GH). This source of A5 GH was used in Examples 63 and 64.

A feed was produced by mixing the source of A5 GH above with triflicacid and heptane to give the feed composition listed in Table 9. Thisexample illustrates a simulated continuous extraction of a feedcontaining esters of glycolic and valeric acids, triflic acid, andheptane with a hydrophilic solvent containing 20% aqueous glycolic acidfor separation of Triflic acid from A5 GH. The feed mixture wassubjected to a cascaded series of twenty-four cross-flow batchextractions to simulate a six-stage continuous counter-currentextraction process, with the feed mixture (20.0 g) introduced on stagesix (from the top) and the aqueous glycolic acid solvent (8.0 g) onstage one (top of extractor). The multi-cycle, cascaded pattern of 24extractions in which one feed mixture charge is added into the firstcycle of the cascade, and multiple hydrophilic solvent charges areintroduced into each cycle of the cascade, and with raffinate andextract compositions introduced to the next cycle of the cascade,results in a set of conditions on the final cycle which have been shownto closely approach the equilibrium composition profile of a continuous,staged, counter-current fractional extractor. For this work, threecycles were found to be sufficient to asymptotically approach continuousextraction equilibrium conditions. The simulated counter-currentextraction technique used herein is well-known to those skilled in theart and is laid out in detail in Treybal (“Liquid Extraction,” 2nd Ed.,McGraw-Hill Book Company, New York, N.Y., 1963, pp. 349-366). The feedcontained 10 weight percent hydrophobic solvent. The hydrophilic solvent(aqueous glycolic acid) to feed (including the heptane) weight ratio was0.4:1.0. The experiment was conducted at room temperature. The finalsimulated raffinate (19.24 g—top product) and extract (8.58 g—bottomproduct) streams were subjected to GC and X-ray analysis to determinethe compositions of the products. Results are given in Table 9 with allpercentages representing weight percent. The percent recovery to theextract is based on the amount of each component in all inputs to theextractor. The percent accountability of each component is equal tototal out/total in as a percentage.

TABLE 9 Simulated Extraction Results Recovery Aq G1 Feed ExtractRaffinate % to Extract Solvent (%) (%) (%) (%) Account (%) Water 80.02.1 59.9 7.4 97 78.2 Heptane 0.0 10.0 0.3 10.1 99 1.2 A5 0.0 46.5 13.145.1 106 11.4 G1 20.0 3.5 14.1 5.6 100 52.4 A5GH 0.0 29.0 5.6 27.1 998.4 G2 0.0 1.1 1.0 0.1 48 86.5 A5G2H 0.0 4.2 0.2 3.5 81 2.6 Triflic 0.02.0 4.6 0.0 100 99.2 Other 0.0 1.7 1.2 1.2 90 32.3

Example 64

Example 63 was repeated using a feed produced by mixing the source of A5GH above with triflic acid to give the feed composition listed in Table10 with the feed (20.0 g) introduced on stage three (from the top), thehydrophobic solvent (10.0 g), toluene, introduced on stage six (from thetop), and the hydrophilic solvent or water wash (8.0 g) introduced onstage one (from top). The final simulated raffinate (11.4 g—hydrophobicproduct) and extract (26.6 g—hydrophilic product) streams were subjectedto GC and X-ray analysis to determine the compositions of the products.Results are given in Table 10.

TABLE 10 Simulated Extraction Results Hydrophilic HydrophilicHydrophobic Product Hydrophobic % Recovery to Feed Solvent (%) Solvent(%) (%) Product (%) extract Toluene 0.00 100.0 0.23 37.32 0.26 Water1.26 100.0 69.53 8.37 78.07 Triflic 2.20 3.83 <0.001 >99.94 G1 5.4725.22 0.43 96.16 A5 39.16 0.72 23.51 1.30 A5GH 50.58 0.06 29.86 0.09other 1.33 0.41 0.51 not determined TOTAL 100.0 100.0 100.0 100.0 100.0%

Example 65

Example 65 illustrates a continuous extraction demonstration of therecovery of triflic acid from a esters of glycolic and valeric acidsfeed stream derived from the hydrocarboxylation of formaldehyde using ahydrophilic solvent comprising 70 wt % G1, 30 wt % water and ahydrophobic solvent comprising 100 wt % toluene. This extraction wascarried out in a Karr column comprising four jacketed glass columnsections (15.9 mm inside diameter, each 501 mm in length) stacked on topof each other. Jacketed glass disengagement sections, 25.4 mm insidediameter and 200 mm in length, were attached to the top and bottom ofthe four extractor sections. The four column sections and twodisengagement sections were joined together with Teflon O-ring gaskets(25 mm thickness) held together with bolted flanges to form the columnbody. Feed ports were fitted into each Teflon O-ring to allow change offeed locations. The total height of the resulting column wasapproximately 2.6 meters. Separate temperature-controlled heating bathswere connected to the jacket of each disengagement zone and one bath tothe combined four column sections to maintain the desired extractiontemperature gradient.

Agitation in the column was supplied by an 3.2 mm diameter Hastelloy276C impeller shaft fitted with seventy-seven Teflon plates, each witheight radial rectangular petals (to provide gaps for liquid flow paths),spaced 25 mm apart in the column sections. The impeller shaft wasattached at the top of the extractor to an electric motor fitted with aconcentric gear to convert rotational motion into reciprocal motion. Theagitator stroke length (i.e., extent of vertical motion) was 19 mm, andvaried from 200 to 350 strokes per minute.

Depending on the chosen continuous phase, the liquid-liquid phaseinterface was maintained in either the top or bottom disengagementsection (in the top section if the less dense phase were continuous,bottom section if the more dense phase were continuous) by visualobservation and manual manipulation of the underflow take-off pump.

Up to three feeds could be supplied to the column via piston pumps fromindependently temperature-controlled jacketed glass vessels of fourliter, two liter, and two liter volumes, while the underflow (moredense) product and the top, overflow (less dense) product were collectedin two-liter glass vessels. The top product collected by gravityoverflow from the upper disengagement section, while the bottoms productflow was controlled by a variable rate piston pump.

Feed locations are designated as follows from the top of the column tothe bottom:

F1: Feed location between top disengagement zone and 1st column section

F2: Feed location between 3^(rd) and 4^(th) column sections

F3: Feed location between 4^(th) column section and bottom disengagementzone

The column was operated continuously for five hours. The feed was thecombined crude hydrocarboxylation reactor product produced in Examples137 and 138 discussed below. The crude hydrocarboxylation reactorproduct was fed at feed location F2, the hydrophilic solvent (70%glycolic acid and 30 wt % water) fed at F1 and the hydrophobic solventfed at F3. The hydrophilic solvent to feed ratio was held at 0.124 to 1on a mass basis, and the hydrophobic solvent to valerate-triflic feedmass ratio was held at 0.59. These conditions resulted in greater than99.0% of the triflic acid being recovered in the polar extract (aqueousextract). Results from this extraction are tabulated below in Table 11.All values are in weight percent.

Triflic acid is recovered in the hydrophilic product stream (extract) ata rate of 99%. About 21.2% of all G1 moieties in the valerate-triflicfeed and hydrophilic solvent were recovered to the hydrophobic raffinatephase, but subtracting out G1 entering in the hydrophilic solvent, therecovery of G1 moieties in the valerate-triflic feed rises to 68.3%.Furthermore, since the original feed to the hydrocarboxylation reactionresulting in the crude hydrocarboxylation product from Examples 137 and138, contained G1, the extraction actually resulted in essentiallycomplete recovery of new G1 moieties created in the reaction Examples137 and 138. Thus, such an extraction is capable of fully separatingtriflic acid from valerate-glycolic esters and producing a concentratedtriflic acid-glycolic acid stream suitable for recycle tohydrocarboxylation.

TABLE 11 Karr Column Continuous Extraction Hydrophilic HydrophobicHydrophilic Hydrophobic Mass Recovery Feed Solvent Solvent ExtractRaffinate Balance to Extract Triflic Acid 2.93 7.74 0.023 100.4 99.0% G113.30 70 46.40 3.50 100.9 78.8% DGA 5.40 13.30 1 117.5 78.8% A5 37 6.8025.50 99.5 7.0% A5GH 26 6.30 17.50 99.5 9.2% A5G2H 7 1.40 5.07 104.87.2% A5G3H 2 0.40 1.26 92.1 8.2% Others 1.47 7.36 0.06 193.6 97.3% Water4.90 30% 10.30 3.55 100.3 44.8% Toluene 100% 3.60 42.54 99.0 2.3% Total100.0 100.0 100% 100.0 100.0 100.3 Flowrate, 10.5 1.3 6.2 3.95 14.1g/min

The following examples illustrate the hydrocarboxylation of either MDAin acetic acid or MDP in propionic acid catalyzed by strongly acidicsolid acid catalysts.

Example 66

MDA (methylene diacetate) or MDP (methylene dipropionate) used in thefollowing Examples were produced from a refluxing mixture ofparaformaldehyde and acetic or propionic anhydride in the presence of asmall amount of sulfuric acid. The reactions were followed by gaschromatography. Upon completion of the reaction, sodium acetate (NaOAc)or propionate were added to the mixture to neutralize the sulfuric acid.The mixture was distilled to give 99% pure methylene dicarboxylate. Thefollowing procedure for methylene diacetate is exemplary: A 5 Lround-bottom flask was fitted with a condenser, thermowell, overheadstirrer, inert gas bubbler, and heating mantle. To this flask was added885 grams of paraformaldehyde followed by 3,324 mL of acetic anhydride.The mixture was then stirred at room temperature and 12 mL ofconcentrated sulfuric acid was added. An exotherm heated the solution toapproximately 80° C. and then the heating mantle was turned on. Themixture was held at reflux for almost 10 hours and sampled periodicallyto check for completion by gas chromatography. Upon completion, 35 g ofNaOAc was added to the mixture to neutralize the sulfuric acid. Themixture was then transferred to another flask along with the NaOAc andpure MDA was distilled.

Example 67

A 50 mL Hastelloy 276C high pressure autoclave was fitted with animpeller, gas inlet tube, sample tube, and thermowell. The autoclave washeated with a heating block, with temperature control provided byfeedback via a thermocouple in the autoclave thermowell. Pure carbonmonoxide gas (>99.9%) was fed to the autoclave via a high pressureregulator. The autoclave was charged with 20% W-heteropoly/silicacatalyst (1.48 g) propionic acid (12.28 g, 0.16 mol) and MDP (14.1 g,0.08 mol) and water (1.4 g, 0.08 mol) and sealed. The autoclave wassecured to the stand and the system was pressurized with 200 psignitrogen and vented. This purging procedure was repeated two times. Theautoclave was then purged with carbon monoxide and pressurized to 200psig carbon monoxide. The temperature in the autoclave was increased to140° C. Upon reaching 140° C., the pressure in the autoclave wasincreased to 1,000 psig carbon monoxide. The reaction was held at theseconditions for 2 hours and then cooled to room temperature and vented.Finally the autoclave was purged with nitrogen and unloaded. Thereaction contents were analyzed by GC. Results are shown in Table 12.

Examples 68-83

The procedure of Example 67 was repeated using either MDP/propionic acidor MDA/acetic acid and water at target equivalents of 1 eq. of MDA(MDP),2 eq. acetic (propionic) acid, and 1 eq. water at a reaction pressure of1000 psig carbon monoxide. The examples were run with the solid catalystand corresponding loading, at the temperature, and for the holding timeshown in Table 12. Calculated yields are also given in Table 12.

TABLE 12 Hydrocarboxylations of Methylene Diacetate (MDA) or MethyleneDipropionate (MDP) Catalyzed by Strongly Acidic Solid Acid Catalysts.loading temp time yield EX catalyst (wt %) (° C.) (h) (%) 67 MDP 20%W-heteropoly/silica 5 140 2 6.5 68 MDP SiO₂/Al₂O₃ 5 140 2 2.0 69 MDA K105 140 2 3.8 70 MDA AMBERLYST 70 5 140 2 18.8 71 MDA SAC-13 9 140 1 47.872 MDA SAC-13 9 160 1 69.8 73 MDA SAC-13 9 180 1 78.8 74 MDA Nafion NR505 140 2 69.4 75 MDA SAC-13 15 160 1 98.6 76 MDA polymer-bound pTSA 5 1402 66 77 MDA AMBERLYST 36 5 140 2 77 78 MDA SMOPEX (4% crosslinking) 5140 3 65 79 MDA SMOPEX (8% crosslinking) 5 160 2 70 80 MDA SMOPEX (12%crosslinking) 5 180 2 66 81 MDP AMBERLYST 36 5 140 2 86 82 MDP SAC-13 10140 2 76 83 MDP SMOPEX (4% crosslinking) 5 140 2 68

Examples 84

A 50 mL Hastelloy 276C high pressure autoclave was fitted with animpeller, gas inlet tube, sample tube, and thermowell. The autoclave washeated with a heating block, with temperature control provided byfeedback via a thermocouple in the autoclave thermowell. Pure carbonmonoxide gas (>99.9%) was fed to the autoclave via a high pressureregulator. The autoclave was charged with AMBERLYST 36 D catalyst (1.43g), propionic acid (12.3 g, 0.166 mol), MDP (14.1 g, 0.088 mol), andwater (1.5 g, 0.083 mol) and sealed. The autoclave was secured to thestand and the system was pressurized with 200 psig nitrogen and vented.This purging procedure was repeated two times. The autoclave was thenpurged with carbon monoxide and pressurized to 500 psig carbon monoxide.The temperature in the autoclave was increased to 140° C. Upon reaching140° C., the pressure in the autoclave was increased to 1,000 psigcarbon monoxide. The reaction was held at these conditions for 2 hoursand then cooled to room temperature and vented. Finally the autoclavewas purged with nitrogen and unloaded. The reaction contents wereanalyzed by GC. The results are shown in Table 13.

Examples 85-91

Example 84 was repeated with the catalyst and catalyst loading andamount of propionic acid and water given in Table 13. Each reaction wasrun at 1000 psig carbon monoxide and at the temperature and for the timeindicated in Table 13. Yield to desired products and selectivity arealso given in Table 13.

TABLE 13 Hydrocarboxylations of MDP Loading A3 Water Temp Time Select.Ex. Catalyst (wt %) (eq) (eq) (° C.) (h) Yield (%) (%) 84 AMBERLYST 36 D5 2.0 1.0 140 2 96 96 85 AMBERLYST 36 D 8 0.14 1.1 140 2 89 94 86AMBERLYST 36 D 5 2.1 1 140 2 86 96 87 AMBERLYST 36 D 5 1.1 1 140 2 78 9588 AMBERLYST 36 D 5 0.15 1 140 2 72 94 89 AMBERLYST 36 D 5 2 0.05 140 22 28 90 AMBERLYST 36 D 5 2 0.05 90 2 3 5 91 AMBERLYST 36 D 5 2 0.5 140 216 66

The following examples illustrate the hydrocarboxylation of MDA inacetic acid catalyzed by various strongly acidic homogeneous catalysts.MDA was prepared as described above in Example 66.

Example 92

To a Hastelloy 276C 300 mL autoclave equipped with a liquid samplingloop and a high pressure addition funnel was added acetic acid (60.05 g,1.0 mol), water (9.0 g, 0.5 mol), and trifluoromethanesulfonic acidcatalyst (0.375 g, 2.5 mmol). The autoclave was heated with a heatingblock, with temperature control provided by feedback via a thermocouplein the autoclave thermowell. Pure carbon monoxide gas (>99.9%) was fedto the autoclave via a high pressure regulator. The MDA (66.26 g, 0.5mol) was added to the addition funnel (blowcase). The autoclave wassealed, flushed with CO and heated to 140° C. under 100 psig carbonmonoxide. The addition funnel containing the MDA was heated to 100° C.Upon reaching 140° C. in the autoclave, the MDA was charged to theautoclave by pressurizing the addition funnel. Immediately uponcompleting the liquid addition, a sample was removed from the autoclave(time zero) and the pressure was adjusted to 1000 psig CO. Thetemperature and pressure were maintained using pure carbon monoxide forthe duration of the 4 hour reaction. Samples were removed from theautoclave at 15 min, 30 min, 45 min, 60 min, 120 min, 180 min and 240min. The samples were analyzed by GC and HPLC. Final conversion andselectivity is given in Table 14.

Examples 93-96

Example 92 was repeated except the acid catalyst and amount were asgiven in Table 14. 2.5 mmol of acid catalyst was used in each case. Thefinal MDA conversions and selectivities are given in Table 14.

TABLE 14 Hydrocarboxylation of MDA in Acetic Acid with a HomogeneousStrong Acid Catalyst. MDA Catalyst Con- MDA Ex. Catalyst charge (g)version Selectivity 92 trifluoromethanesulfonic acid 0.375 99 96 93tetrafluoroethanesulfonic acid 0.455 96 96 94bis(trifluoromethane)sulfonylamide 0.70 99 95 95nonafluorobutanesulfonic acid 0.75 99 95 96 sulfuric acid 0.256 81 53

The following examples illustrate the effect of feed water content,temperature, pressure, and catalyst level on the hydrocarboxylation oftrioxane or paraformaldehyde with valeric acid and glycolic acid assolvents/reactants and triflic acid as catalyst.

Example 97

The continuous hydrocarboxylation was carried out using a reactor systemcontaining Hastelloy 276C autoclave (125 ml nominal volume) andassociated feed and product storage equipment. The high pressureautoclave was fitted with a hollow shaft Rushton turbine impeller (forgas introduction and dispersion), baffles, thermowell, gas inlet tube,and sip tube to maintain liquid level at approximately 90 ml and toprovide an exit for product effluent. The autoclave was heatedelectrically by a band heater, with temperature control provided byfeedback via a K-type thermocouple in the autoclave thermowell.

Pure carbon monoxide gas (>99.9%) was fed to the autoclave via a highpressure flow controller. The gas entered the body of the autoclave viagroves in the impeller bearings. The off gas flow rate was monitored bya dry bubble-type flow meter. The flow rates of the two liquid feedswere controlled to a precision of 0.001 ml/min with double-barreled 500ml high-precision syringe pumps connected to stirred feed vessels.

Reactor effluent passed through heated Hastelloy tubing, an automaticpressure control valve (research control valve), and into a 1.0 Lheatable Hastelloy collection vessel. The effluent collection vessel wasfitted with a chilled coiled condenser. The gas outlet from the effluenttank was connected to a manual back pressure regulator to maintainvessel pressure at 40-100 psig. Temperatures, pressures, and otherrelevant system parameters were recorded automatically by a distributedcontrol system.

Feed 1 (0.4 g/min) and Feed 2 (0.39 g/min), having the composition givenin Table 15 were fed to the reactor. Carbon monoxide was fed at a rateof 998 SCCM as noted in Table 16. The reaction was run at a pressure of1500 psig and a temperature of 170° C. with a residence time of 85minutes. Table 16 also gives feed molar ratios and the source offormaldehyde. For Example 107 the source was trioxane.

Samples of the hydrocarboxylation reaction were analyzed by HPLC.Conversion, space-time yield, and selectivity of reacted formaldehyde toend products are summarized in Table 17. Any glycolic acid fed wassubtracted out for conversion and yield calculations. Methanol waspresent as free methanol, methyl glycolate, and methyl valerate, and wasconverted to free methanol, glycolic acid, and valeric acid by theanalytical method.

Examples 98-143

Example 97 was repeated with the liquid feeds given in Table 15, thecarbon monoxide flow rate, source of formaldehyde, feed molar ratios,pressure, temperature, residence time given in Table 16. Conversion,space-time yield, and selectivity of reacted formaldehyde to endproducts are summarized in Table 17.

TABLE 15 Feed 1 and Feed 2: Rates and Compositions Feed 1, mass % Feed 2Feed 2 mass % Ex # Feed 1 g/min F0 A5 G1 water Triflic g/min A5 Triflic97 0.40 21.1 71.9 0.0 3.8 3.2 0.39 100.00 0.00 98 0.39 21.1 71.9 0.0 3.83.2 0.39 100.00 0.00 99 0.39 21.1 71.9 0.0 3.8 3.2 0.39 100.00 0.00 1000.39 21.1 71.9 0.0 3.8 3.2 0.39 100.00 0.00 101 0.39 21.1 71.9 0.0 3.83.2 0.39 100.00 0.00 102 0.39 21.1 71.9 0.0 3.8 3.2 0.39 100.00 0.00 1030.39 21.1 71.9 0.0 3.8 3.2 0.39 100.00 0.00 104 0.61 21.1 71.9 0.0 3.83.2 0.62 100.00 0.00 105 0.61 21.1 71.9 0.0 3.8 3.2 0.62 100.00 0.00 1060.39 21.1 71.9 0.0 3.8 3.2 0.39 100.00 0.00 107 0.61 21.1 71.9 0.0 3.83.2 0.62 100.00 0.00 108 0.39 21.8 74.2 0.0 3.9 0.0 0.39 95.78 4.22 1090.39 21.8 74.2 0.0 3.9 0.0 0.39 95.78 4.22 110 0.39 21.8 74.2 0.0 3.90.0 0.39 95.78 4.22 111 0.39 21.8 74.2 0.0 3.9 0.0 0.39 95.78 4.22 1120.39 21.8 74.2 0.0 3.9 0.0 0.39 95.78 4.22 113 0.64 26.8 68.4 0.0 4.80.0 0.17 85.01 14.99 114 0.64 26.8 68.4 0.0 4.8 0.0 0.17 85.01 14.99 1150.64 26.8 68.4 0.0 4.8 0.0 0.17 85.01 14.99 116 0.64 26.8 68.4 0.0 4.80.0 0.17 85.01 14.99 117 0.64 26.8 68.4 0.0 4.8 0.0 0.17 85.01 14.99 1180.68 23.7 0.0 60.0 9.9 6.4 0.36 100.00 0.00 119 0.68 23.7 0.0 60.0 9.96.4 0.36 100.00 0.00 120 0.68 23.7 0.0 60.0 9.9 6.4 0.36 100.00 0.00 1210.68 23.7 0.0 60.0 9.9 6.4 0.32 100.00 0.00 122 0.68 23.7 0.0 60.0 9.96.4 0.36 100.00 0.00 123 0.68 23.7 0.0 60.0 9.9 6.4 0.36 100.00 0.00 1240.43 34.0 0.0 51.7 14.3 0.0 0.52 92.93 7.07 125 0.43 34.0 0.0 51.7 14.30.0 0.52 92.93 7.07 126 0.43 34.0 0.0 51.7 14.3 0.0 0.52 92.93 7.07 1270.43 34.0 0.0 51.7 14.3 0.0 0.52 92.93 7.07 128 0.43 34.0 0.0 51.7 14.30.0 0.52 92.93 7.07 129 0.43 34.0 0.0 51.7 14.3 0.0 0.52 92.93 7.07 1300.43 34.0 0.0 51.7 14.3 0.0 0.52 92.93 7.07 131 0.65 25.1 0.0 63.6 4.56.8 0.38 100.00 0.00 132 0.65 25.1 0.0 63.6 4.5 6.8 0.38 100.00 0.00 1330.65 25.1 0.0 63.6 4.5 6.8 0.38 100.00 0.00 134 0.65 25.1 0.0 63.6 4.56.8 0.38 100.00 0.00 135 0.65 25.1 0.0 63.6 4.5 6.8 0.38 100.00 0.00 1360.65 25.1 0.0 63.6 4.5 6.8 0.38 100.00 0.00 137 0.47 32.5 0.0 61.7 5.80.0 0.54 92.61 7.39 138 0.47 32.5 0.0 61.7 5.8 0.0 0.54 92.61 7.39 1390.47 32.5 0.0 61.7 5.8 0.0 0.54 92.61 7.39 140 0.47 32.5 0.0 61.7 5.80.0 0.54 92.61 7.39 141 0.47 32.5 0.0 61.7 5.8 0.0 0.54 92.61 7.39 1420.47 32.5 0.0 61.7 5.8 0.0 0.54 92.61 7.39 143 0.47 32.5 0.0 61.7 5.80.0 0.54 92.61 7.39%

TABLE 16 Overall Feed Molar Ratios and Reaction Conditions CO Res FlowF0 Feed Molar Ratio Press Temp Time Ex SCCM Type HFR A5 G1 water TriflicPsig Celsius min 97 998.0 Trioxane 1.0 2.0 0.0 0.3 0.030 1500 170 85 98998.0 Trioxane 1.0 2.0 0.0 0.3 0.030 1001 170 87 99 998.0 Trioxane 1.02.0 0.0 0.3 0.030 1498 160 87 100 998.0 Trioxane 1.0 2.0 0.0 0.30 0.0301501 150 87 101 998.0 Trioxane 1.0 2.0 0.0 0.30 0.030 747 160 87 102998.0 Trioxane 1.0 2.0 0.0 0.30 0.030 997 160 87 103 998.0 Trioxane 1.02.0 0.0 0.30 0.030 1500 170 87 104 998.0 Trioxane 1.0 2.0 0.0 0.30 0.030749 150 55 105 998.0 Trioxane 1.0 2.0 0.0 0.30 0.030 750 140 55 106998.0 Trioxane 1.0 2.0 0.0 0.30 0.030 753 170 87 107 998.0 Trioxane 1.02.0 0.0 0.30 0.030 751 150 55 108 998.0 Trioxane 1.0 2.0 0.0 0.30 0.0301501 143 87 109 998.0 Trioxane 1.0 2.0 0.0 0.30 0.030 1495 160 87 110998.0 Trioxane 1.0 2.0 0.0 0.30 0.030 1498 170 87 111 998.0 Trioxane 1.02.0 0.0 0.30 0.030 1500 170 87 112 998.0 Trioxane 1.0 2.0 0.0 0.30 0.0301499 170 87 113 998.0 Trioxane 1.0 1.0 0.0 0.30 0.030 1498 170 87 114998.0 Trioxane 1.0 1.0 0.0 0.30 0.030 1003 170 87 115 998.0 Trioxane 1.01.0 0.0 0.30 0.030 499 170 87 116 998.0 Trioxane 1.0 1.0 0.0 0.30 0.030999 160 87 117 998.0 Trioxane 1.0 1.0 0.0 0.30 0.030 506 165 87 118998.0 PF 1.0 0.7 1.0 0.70 0.054 1497 180 80 119 998.0 PF 1.0 0.7 1.00.70 0.054 1503 180 80 120 998.0 PF 1.0 0.7 1.0 0.70 0.054 1497 180 80121 998.0 PF 1.0 0.7 1.0 0.70 0.054 1498 180 83 122 998.0 PF 1.0 0.7 1.00.70 0.054 1504 180 80 123 998.0 PF 1.0 0.7 1.0 0.70 0.054 1504 180 80124 998.0 PF 1.0 1.0 0.6 0.70 0.054 1492 180 80 125 998.0 PF 1.0 1.0 0.60.70 0.054 1003 180 80 126 998.0 PF 1.0 1.0 0.6 0.70 0.054 500 180 80127 998.0 PF 1.0 1.0 0.6 0.70 0.054 995 170 80 128 998.0 PF 1.0 1.0 0.60.70 0.054 502 170 80 129 998.0 PF 1.0 1.0 0.6 0.70 0.054 1000 160 80130 998.0 PF 1.0 1.0 0.6 0.70 0.054 498 160 80 131 498.0 PF 1.0 0.7 1.00.30 0.054 1507 170 80 132 498.0 PF 1.0 0.7 1.0 0.30 0.054 1499 180 80133 498.0 PF 1.0 0.7 1.0 0.30 0.054 1503 180 80 134 498.0 PF 1.0 0.7 1.00.30 0.054 1498 180 80 135 498.0 PF 1.0 0.7 1.0 0.30 0.054 1003 160 80136 498.0 PF 1.0 0.7 1.0 0.30 0.054 1501 170 80 137 498.0 PF 1.0 1.0 0.80.30 0.054 1500 180 76 138 498.0 PF 1.0 1.0 0.8 0.30 0.054 999 180 76139 498.0 PF 1.0 1.0 0.8 0.30 0.054 500 180 76 140 498.0 PF 1.0 1.0 0.80.30 0.054 999 170 76 141 498.0 PF 1.0 1.0 0.8 0.30 0.054 500 170 76 142498.0 PF 1.0 1.0 0.8 0.30 0.054 1004 160 76 143 498.0 PF 1.0 1.0 0.80.30 0.054 500 160 76

TABLE 17 Selectivity, Conversion, and Space-Time Yield Results Space %F0 Time Molar Exam- Con- Yield Selectivity ple version gmol/l-hr G1 A1DG MGH MeOH 97 94.7 1.51 96.42 1.02 1.55 0.00 1.02 98 93.0 1.44 96.710.93 1.42 0.00 0.93 99 93.5 1.42 96.41 1.23 1.13 0.00 1.23 100 92.5 0.9396.22 1.36 1.06 0.00 1.36 101 87.1 1.36 96.17 1.41 0.80 0.43 1.19 10290.3 1.32 96.92 1.09 0.91 0.00 1.09 103 96.3 1.37 96.90 0.87 1.36 0.000.87 104 75.3 1.59 91.30 3.85 0.99 0.00 3.85 105 56.3 1.22 85.32 7.160.10 0.50 6.91 106 89.4 1.41 96.55 1.05 1.34 0.00 1.05 107 67.5 1.8992.15 3.56 0.72 0.00 3.56 108 86.2 1.42 94.31 2.33 0.98 0.12 2.26 10991.3 1.55 96.12 1.26 1.36 0.00 1.26 110 93.5 1.60 96.32 1.05 1.58 0.001.05 111 95.2 1.59 96.10 1.13 1.64 0.00 1.13 112 90.9 1.55 96.71 0.931.42 0.00 0.93 113 62.6 1.79 91.65 2.07 4.07 0.19 1.97 114 54.5 1.8491.64 0.47 7.42 0.00 0.47 115 86.6 2.72 92.16 2.45 2.62 0.56 2.17 11684.4 2.84 93.10 1.93 3.03 0.00 1.93 117 80.7 2.56 94.18 1.38 2.88 0.371.19 118 90.2 2.24 89.72 2.00 5.69 0.73 1.64 119 90.4 2.49 90.79 1.675.85 0.00 1.67 120 90.1 2.69 94.24 1.47 2.82 0.00 1.47 121 89.1 2.6692.90 1.83 3.07 0.31 1.68 122 90.0 2.47 93.07 1.67 3.10 0.72 1.31 12390.2 2.60 93.35 1.69 2.94 0.66 1.36 124 91.7 2.37 93.41 1.71 3.11 0.111.66 125 85.7 2.13 91.14 3.20 2.01 0.90 2.75 126 76.4 1.44 79.78 8.412.09 1.83 7.49 127 75.5 2.40 90.60 3.53 2.16 0.36 3.35 128 59.9 1.7883.27 7.20 1.43 0.85 6.78 129 66.5 0.92 70.09 11.5 2.31 7.69 7.75 13053.4 0.57 58.03 20.1 0.93 0.86 19.68 131 89.5 2.25 89.86 2.62 3.94 1.491.87 132 94.9 2.87 92.05 1.47 4.53 0.79 1.07 133 95.2 2.46 91.01 1.714.98 0.92 1.25 134 92.9 2.46 92.89 1.43 4.02 0.37 1.24 135 83.0 1.9289.48 3.19 3.45 1.21 2.58 136 92.5 2.53 91.90 1.63 4.28 0.72 1.27 13793.0 2.62 93.77 1.51 2.95 0.53 1.24 138 93.6 2.82 94.21 1.37 2.96 0.171.29 139 87.1 2.35 89.56 3.53 2.91 0.81 3.13 140 90.4 2.48 93.64 1.722.84 0.00 1.72 141 80.0 2.12 87.08 4.91 2.46 0.88 4.47 142 82.0 2.2890.50 3.24 2.44 1.13 2.68 143 71.6 2.05 86.67 5.24 2.30 0.48 5.00

These examples illustrate the effect of feed water content, temperature,pressure, and catalyst level on the hydrocarboxylation of formaldehyde(trioxane) with triflic acid as catalyst, with n-butyric acid andglycolic acid as solvent/reactant.

Examples 144-147

Example 97 was repeated with only one feed at 0.91 g/min. The feedcontained 14.6 wt % paraformaldehyde, 6.2% water, 28.8 wt % butyricacid, 48.2 wt % glycolic acid, and 2.2 wt % triflic acid. The feed molarratio was paraformaldehyde (1.0), water (0.7), glycolic acid (1.5), andtriflic acid (0.03). The hold-up time was 95 minutes. The feed rate ofcarbon monoxide was 498 SCCM. The operating pressure and temperature,along with conversion, space-time yield, and selectivity of reactedformaldehyde to end products are summarized in Table 18.

TABLE 18 Reactor Conditions, Selectivity, Conversion, and Space-TimeYield Results Molar Space-Time Temp Pressure % F0 Selectivity Yield ExCelsius psig Conversion G1 A1 MeOH MGH DG gmol/l-hr 144 150 935 40.170.1 13.9 13.9 0.0 2.2 1.04 145 170 1199 71.2 83.3 5.6 5.6 1.5 4.1 2.08146 190 1199 88.3 89.6 1.8 1.8 1.6 5.2 2.91 147 170 1745 77.5 88.0 3.63.6 0.8 3.8 2.38

The following examples illustrate the effect of feed water content,temperature, pressure and catalyst level on the hydrocarboxylation ofmethylene diacetate with triflic acid as catalyst.

Examples 148-153

Example 97 was repeated but with MDA as the source of formaldehyde andat the feed rates and compositions noted in Table 19. In theseexperiments moles of MDA represent the formaldehyde equivalent, whileacetic acid equivalents are calculated as the sum of free acetic acidfed and two times the MDA molar flow rate. The feed molar ratios,temperature, pressure, and hold-up time are given in Table 20.Conversion, space-time yield, and selectivity of reacted formaldehyde toend products are summarized in Table 21. All methanol was present asmethyl acetate, and was also converted to free methanol and acetic acidby the analytical method.

TABLE 19 Feed 1 and 2 Rates and Compositions Feed 1 Feed 1, mass % Feed2 Feed 2 mass % Ex g/min MDA A2 water g/min A2 water Triflic 148 0.69100 0 0 0.71 86.7 1.3 0.30 149 0.69 100 0 0 0.79 69.5 29.2 1.30 150 0.69100 0 0 0.79 69.5 29.2 1.30 151 0.69 100 0 0 0.79 69.5 29.2 1.30 1521.10 56.4 7.7 35.9 0.32 99 0 1 153 0.03 56.4 7.7 35.0 0.32 96 0 4

TABLE 20 Overall Feed Ratios and Reaction Conditions Feed Molar RatioTemp Press Res Time Ex F0 water A2 Triflic Celsius psig minutes 148 1.01.2 3.8 0.002 190 650 70 149 1.0 1.4 3.0 0.007 200 600 67 150 1.0 1.43.0 0.007 190 600 67 151 1.0 1.4 3.0 0.007 180 600 67 152 1.0 1.0 4.50.005 190 1300 69 153 1.0 1.0 4.5 0.020 170 1300 73

TABLE 21 Selectivity, Conversion, and Space-Time Yield Results MolarSpace-Time % HFr Selectivity Yield Ex Conv G1 A1 MeOH MGH DG gmol/l-hr148 70 95.8 1.75 1.75 0.00 0.85 2.20 149 75 90.8 1.7 1.7 0.00 5.8 2.00150 70 94.2 1.5 1.5 0.00 2.8 2.00 151 50 92.9 1.8 1.7 0.3 3.1 1.20 15277 93.1 1.7 1.3 0.7 3.1 2.60 153 95 93.3 1.7 1.4 0.7 2.9 2.80

The following examples illustrate the effect of feed water content,temperature, pressure, and catalyst level on the hydrocarboxylation ofparaformaldehyde with sulfuric acid as catalyst.

Examples 154-159

Example 97 was repeated using only one feed stream with the feed rateand compositions shown in Table 22. The feed mixture was prepared bymixing, water, H₂SO₄ and HGH in a tank heated to 60° C. Paraformaldehydewas added with stirring until complete dissolution occurred. The feedwas kept at 60° C. throughout the reaction period to ensure no solidformaldehyde precipitated. The operating conditions along with reactionpressure, temperature and residence time are summarized in Tables 22 and23.

Conversion, space-time yield, and selectivity of reacted formaldehyde toend products are summarized in Table 24. During analysis, glycolic acidoligomers and other forms of glycolic acid were hydrolyzed and convertedto free monomeric glycolic acid equivalents. The selectivity ofconversion of formaldehyde is reported as free glycolic acidequivalents. Methanol was present as both free methanol and methylglycolate, and was converted to free methanol and glycolic acid by theanalytical method.

TABLE 22 Feed 1: Rate and Composition Ex g/min Paraformaldehyde water G1H₂SO₄ 154 0.68 13.8 8.3 70.2 7.7 155 1.01 13.8 11.7 70.0 4.5 156 1.0113.8 11.6 70.0 4.5 157 1.66 13.0 17.2 66.0 3.8 158 1.02 14.4 4.3 73.28.0 159 0.94 29.8 28.6 37.8 3.8

TABLE 23 Overall Feed Ratios and Reaction Conditions Res Feed MolarRatio Temp Press Time Ex Paraformaldehyde water G1 H₂SO₄ Celsius psigminutes 154 1.0 1.0 2.0 0.170 170 1502 180 155 1.0 1.4 2.0 0.100 200 699120 156 1.0 1.4 2.0 0.100 190 703 120 157 1.0 2.2 2.0 0.089 205 2603 72158 1.0 0.5 2.0 0.170 190 1901 120 159 1.0 1.6 0.5 0.039 205 2605 120

TABLE 24 Selectivity, Conversion, and Space-Time Yield Results MolarSpace-Time % F0 Selectivity Yield Ex Conv G1 A1 DG MGH MeOH gmol/l-hr154 92 94.06 1.06 3.82 0.00 1.06 1.73 155 87 64.56 10.72 5.56 16.86 2.291.05 156 85 70.00 10.80 3.00 10.40 5.70 1.55 157 93 89.22 2.90 4.12 1.722.04 3.55 158 97 84.63 1.24 11.97 1.85 0.32 2.51 159 95 89.96 3.04 2.912.11 1.98 4.94

We claim:
 1. A process for the preparation of glycolic acid, comprising(A) feeding carbon monoxide, aqueous formaldehyde, a homogeneous acidcatalyst, and a carboxylic acid comprising 3-6 carbon atoms to ahydrocarboxylation reaction zone to produce an effluent comprising saidhomogeneous acid catalyst and esters of glycolic and carboxylic acids;(B) recovering said homogeneous acid catalyst from said effluent byextracting said effluent with a first hydrophilic solvent to form afirst aqueous extract phase comprising a major amount of saidhomogeneous acid catalyst contained in said effluent and a first organicraffinate phase comprising a major amount of said esters of glycolic andcarboxylic acids contained in said effluent; (C) separating said firstorganic raffinate phase and said first aqueous extract phase; and (D)recycling said first aqueous extract phase to step (A).
 2. The processaccording to claim 1, wherein said feeding of said carboxylic acid andsaid aqueous formaldehyde in step (A) occurs at a molar ratio ofcarboxylic acid:formaldehyde of from 0.5:1 to 6:1 and said feeding ofsaid homogeneous acid catalyst and said aqueous formaldehyde in step (A)occurs at a molar ratio of homogeneous acid catalyst:formaldehye of from0.001:1 to 0.1:1.
 3. The process according to claim 1, wherein saidfeeding of said carboxylic acid and said aqueous formaldehyde in step(A) occurs at a molar ratio of carboxylic acid:formaldehyde of from0.5:1 to 4:1 and said feeding of said homogeneous acid catalyst and saidaqueous formaldehyde in step (A) occurs at a molar ratio of homogeneousacid catalyst:formaldehye of from 0.01:1 to 0.07:1.
 4. The processaccording to claim 1, wherein said feeding of said carboxylic acid andsaid aqueous formaldehyde in step (A) occurs at a molar ratio ofcarboxylic acid:formaldehyde of from 0.5:1 to 2.5:1 and said feeding ofsaid homogeneous acid catalyst and said aqueous formaldehyde in step (A)occurs at a molar ratio of homogeneous acid catalyst:formaldehye of from0.01:1 to 0.07:1.
 5. The process according to claim 1, wherein saidfirst hydrophilic solvent comprises 15 weight percent to 100 weightpercent water and 0 weight percent to 85 weight percent glycolic acid,each based on a total first hydrophilic solvent weight basis, whereinsaid extracting of said effluent occurs further with a first hydrophobicsolvent selected from at least one of the group consisting ofhydrocarbons having from 6 to 20 carbon atoms and ethers having from 4to 20 carbon atoms thereof.
 6. The process according to claim 1, whereinsaid carboxylic acid is selected from at least one of the groupconsisting of propionic acid, n-butyric acid, i-butyric acid, 2-methylbutyric acid, n-valeric acid, and i-valeric acid.
 7. The processaccording to claim 1, wherein said carboxylic acid is selected from atleast one of the group consisting of 2-methyl butyric acid, n-valericacid, and i-valeric acid.
 8. The process according to claim 1, whereingreater than 90 weight percent of said esters of glycolic and carboxylicacids are recovered in said first organic raffinate phase and whereingreater than 95 weight percent of said homogeneous acid catalyst isrecovered in said first aqueous extract phase.
 9. The process accordingto claim 1, wherein said extracting in step (B) occurs in a continuouscounter-current first extractor, wherein said first aqueous extractphase exits the bottom of said first extractor and said first organicraffinate phase exits the top of said first extractor, wherein saidfirst hydrophilic solvent is fed to said first extractor above saideffluent, and wherein the feed ratio of said first hydrophilic solventto said effluent ranges from 0.1:1 to 20:1 on a weight basis.
 10. Theprocess according to claim 5, wherein said extracting in step (B) occursin a continuous counter-current first extractor, wherein said firstaqueous extract phase exits the bottom of said first extractor and saidfirst organic raffinate phase exits the top of said first extractor,wherein said first hydrophilic solvent is fed to said first extractorabove said effluent, and wherein the feed ratio of said firsthydrophilic solvent to said effluent ranges from 0.1:1 to 20:1 on aweight basis, further comprising feeding said first hydrophobic solventto said first extractor, wherein the feed ratio of said firsthydrophobic solvent to said effluent ranges from 0.01:1 to 5:1 on aweight basis, and wherein said hydrophobic solvent is selected from thegroup consisting of hexane, cyclohexane, heptane, octane, decane,benzene, toluene, xylene, isoparaffinic mixed hydrocarbons having aboiling range between 90 and 325° C., methyl naphthalene, diethyl ether,dipropyl ether, diisopropyl ether, dibutyl ethers, methyl tertiary-butylether, and methyl tertiary-amyl ether.
 11. The process according toclaim 9, wherein said feed ratio of said first hydrophilic solvent tosaid effluent ranges from 0.5:1 to 4:1.
 12. The process according toclaim 1, wherein said aqueous formaldehyde comprises 35 weight percentto 85 weight percent formaldehyde, based on the total weight of saidaqueous formaldehyde, the molar ratio of carbon monoxide to formaldehyderanges from 1:1 to 10:1, and said hydrocarboxylation reaction zone isoperated at a pressure of from 35 bar gauge to 200 bar gauge and atemperature of from 120° C. to 220° C.
 13. The process according toclaim 1, wherein said homogeneous acid catalyst is selected from atleast one of the group consisting of hydrochloric acid, hydrobromicacid, hydriodic acid, hydrofluoric acid, perchloric acid, phosphoricacid, nitric acid, sulfuric acid, trifluoroacetic acid, methanesulfonicacid, trifluoromethanesulfonic acid, fluorosulfonic acid, chlorosulfonicacid, benzenesulfonic acid, toluenesulfonic acid,methylsulfonylmethanesulfonic acid, methanetrisulfonic acid,bis(methylsulfonyl)methanesulfonic acid,1,1,2,2-tetrafluoroethanesulfonic acid, nonafluorobutanesulfonic acid,and bis(trifluoromethyl)sulfonylamide.
 14. The process according toclaim 1, wherein said homogeneous acid catalyst is selected from atleast one of the group consisting of sulfuric acid,trifluoromethanesulfonic acid, 1,1,2,2-tetrafluoroethanesulfonic acid,bis(trifluoromethyl)sulfonylamide, and nonafluorobutanesulfonic acid.15. The process according to claim 1, wherein said homogeneous acidcatalyst comprises trifluoromethanesulfonic acid.
 16. The processaccording to claim 1, further comprising (E) hydrolyzing said firstorganic raffinate phase to produce a hydrolyzed mixture comprisingglycolic acid and said carboxylic acid; (F) recovering said carboxylicacid from said hydrolyzed mixture by extracting said hydrolyzed mixturewith a second hydrophobic solvent selected from at least one of thegroup consisting of esters having from 4 to 20 carbon atoms, ethershaving from 4 to 20 carbon atoms, ketones having from 4 to 20 carbonatoms, and hydrocarbons having from 6 to 20 carbon atoms to form asecond aqueous raffinate phase comprising a major amount of saidglycolic acid contained in said hydrolyzed mixture and a second organicextract phase comprising a major amount of said carboxylic acidcontained in said hydrolyzed mixture; (G) separating said second aqueousraffinate phase and said second organic extract phase; and (H)separating said second organic extract phase into said secondhydrophobic solvent and said carboxylic acid, recycling said secondhydrophobic solvent to step (F), and recycling said carboxylic acid tostep (A).
 17. The process according to claim 16, further comprising (I)reacting a first ethylene glycol with said second aqueous raffinatephase while simultaneously removing water to produce an esterificationeffluent comprising glycolate ester oligomers and glycolic acidoligomers and an overhead stream comprising water; and (J) reactinghydrogen with said esterification effluent to produce a second ethyleneglycol, separating said second ethylene glycol into a product ethyleneglycol and said first ethylene glycol, and recycling said first ethyleneglycol to step (I).
 18. The process according to claim 5, wherein saidfirst hydrophobic solvent is separated from said esters of glycolic andcarboxylic acids contained in said first organic raffinate phase andsaid first hydrophobic solvent is recycled to step (B).
 19. The processaccording to claim 16, wherein said first hydrophobic solvent and saidsecond hydrophobic solvent are the same.
 20. A process for thepreparation of glycolic acid, comprising (A) feeding carbon monoxide,aqueous formaldehyde, a homogeneous acid catalyst, and carboxylic acidselected from at least one of the group consisting of propionic acid,n-butyric acid, i-butyric acid, 2-methyl butyric acid, n-valeric acid,and i-valeric acid to a hydrocarboxylation reaction zone to produce aneffluent comprising said homogeneous acid catalyst and esters ofglycolic and carboxylic acids; (B) recovering said homogeneous acidcatalyst from said effluent by extracting said effluent with a firsthydrophilic solvent comprising 15 weight percent to 100 weight percentwater and 0 weight percent to 85 weight percent of glycolic acid, eachon a total first hydrophilic solvent weight basis, and optionally with afirst hydrophobic solvent selected from at least one of the groupconsisting of hexane, cyclohexane, heptane, octane, decane, benzene,toluene, xylene, isoparaffinic mixed hydrocarbons having a boiling rangebetween 90 and 325° C., methyl naphthalene, diethyl ether, dipropylether, diisopropyl ether, dibutyl ether, methyl tertiary-butyl ether,and methyl tertiary-amyl ether to form a first aqueous extract phasecomprising a major amount of said homogeneous acid catalyst contained insaid effluent and a first organic raffinate phase comprising a majoramount of said esters of glycolic and carboxylic acids contained in saideffluent; (C) separating said first organic raffinate phase and saidfirst aqueous extract phase; and (D) recycling said first aqueousextract phase to step (A).
 21. The process according to claim 20,wherein said feeding of said carboxylic acid and said aqueousformaldehyde in step (A) occurs at a molar ratio of carboxylicacid:formaldehyde of from 0.5:1 to 4:1 and said feeding of saidhomogeneous acid catalyst and said aqueous formaldehyde in step (A)occurs at a molar ratio of homogeneous acid catalyst:formaldehye of from0.01:1 to 0.07:1.
 22. The process according to claim 20, wherein saidfeeding of said carboxylic acid and said aqueous formaldehyde in step(A) occurs at a molar ratio of carboxylic acid:formaldehyde of from0.5:1 to 2.5:1 and said feeding of said homogeneous acid catalyst andsaid aqueous formaldehyde in step (A) occurs at a molar ratio ofhomogeneous acid catalyst:formaldehye of from 0.01:1 to 0.07:1.
 23. Theprocess according to claim 20, wherein said extraction occurs with saidfirst hydrophobic solvent and said first hydrophobic solvent is selectedfrom at least one of the group consisting of hexane, heptane, toluene,xylene, and methyl tertiary-butyl ether.
 24. The process according toclaim 20, wherein said carboxylic acid is selected from at least one ofthe group consisting of 2-methyl butyric acid, n-valeric acid, andi-valeric acid.
 25. The process according to claim 20, wherein greaterthan 90 weight percent of said esters of glycolic and carboxylic acidsare recovered in said first organic raffinate phase and wherein greaterthan 95 weight percent of said homogeneous acid catalyst is recovered insaid first aqueous extract phase.
 26. The process according to claim 20,wherein said extracting in step (B) occurs in a continuouscounter-current first extractor, wherein said first aqueous extractphase exits the bottom of said first extractor and said first organicraffinate phase exits the top of said first extractor, wherein saidfirst hydrophilic solvent is fed to said first extractor above saideffluent, and wherein the feed ratio of said first hydrophilic solventto said effluent ranges from 0.5:1 to 4:1 on a weight basis.
 27. Theprocess according to claim 26, further comprising feeding said firsthydrophobic solvent to said first extractor, wherein the feed ratio ofsaid first hydrophobic solvent to said effluent ranges from 0.01:1 to5:1 on a weight basis, and wherein the feed ratio of said firsthydrophilic solvent to said effluent ranges from 0.5:1 to 4:1 on aweight basis.
 28. The process according to claim 20, wherein saidaqueous formaldehyde comprises 35 weight percent to 85 weight percentformaldehyde, based on the total weight of said aqueous formaldehyde,the molar ratio of carbon monoxide to formaldehyde ranges from 1:1 to10:1, and said hydrocarboxylation reaction zone is operated at apressure of from 35 bar gauge to 200 bar gauge and a temperature of from120° C. to 220° C.
 29. The process according to claim 20, furthercomprising (E) hydrolyzing said first organic raffinate phase to producea hydrolyzed mixture comprising glycolic acid and said carboxylic acid;(F) recovering said carboxylic acid from said hydrolyzed mixture byextracting said hydrolyzed mixture with a second hydrophobic solventselected from at least one of the group consisting of n-propyl acetate,i-propyl acetate, n-butyl acetate, i-butyl acetate, s-butyl acetate,methyl propionate, ethyl propionate, i-propyl propionate, methyltertiary-butyl ether, methyl i-butyl ketone, methyl i-propyl ketone,methyl propyl ketone, and toluene to form a second aqueous raffinatephase comprising a major amount of said glycolic acid contained in saidhydrolyzed mixture and a second organic extract phase comprising a majoramount of said carboxylic acid contained in said hydrolyzed mixture; (G)separating said second aqueous raffinate phase and said second organicextract phase; and (H) separating said second organic extract phase intosaid second hydrophobic solvent and said carboxylic acid, recycling saidsecond hydrophobic solvent to step (F), and recycling said carboxylicacid to step (A).
 30. The process according to claim 29, furthercomprising (I) reacting a first ethylene glycol with said second aqueousraffinate phase while simultaneously removing water to produce anesterification effluent comprising glycolate ester oligomers andglycolic acid oligomers and an overhead stream comprising water; and (J)reacting hydrogen with said esterification effluent to produce a secondethylene glycol, separating said second ethylene glycol into a productethylene glycol and said first ethylene glycol, and recycling said firstethylene glycol to step (I).
 31. The process according to claim 20,wherein said first hydrophobic solvent is separated from said firstorganic raffinate phase and recycled to step (B).
 32. The processaccording to claim 29, wherein said first hydrophobic solvent and saidsecond hydrophobic solvent are the same.